Conference Program & Book of Abstracts

Transcription

1

2

3 1 X International Conference for Professionals and Young Scientists "LOW TEMPERATURE PHYSICS" in memory of B.Verkin for his 100th birthday anniversary June 3-7, 2019 Conference Program & Book of Abstracts Kharkiv 2019

4 2 X International Conference for Professionals & Young Scientists Low Temperature Physics (ICPYS LTP 2019) UDK I-69 BBK Scientific Edition Scientific International Conference Conference Program and Book of Abstracts X International Conference for Professionals & Young Scientists LOW TEMPERATURE PHYSICS ICPYS LTP 2019 in memory of B.Verkin for his 100th birthday anniversary Organised by B. Verkin Institute for Low Temperature Physics and Engineering (ILTPE) of the NAS of Ukraine Council of Young Scientists of B. Verkin ILTPE of NAS of Ukraine June 3-7, 2019 Kharkiv, Ukraine I-69 X International Conference for Professionals & Young Scientists LOW TEMPERATURE PHYSICS (ICPYS LTP 2019) in memory of B.Verkin for his 100th birthday anniversary (June 3-7, 2019, Kharkiv): Conference Program and Book of Abstracts / Editor: Olena Vatazhuk. Kharkiv: FOP Panov A.M., p. ISBN This book is the proceedings of the X International Conference for Professionals & Young Scientists LOW TEMPERATURE PHYSICS ICPYS LTP 2019 in memory of B.Verkin for his 100th birthday anniversary, and contains 121 peer-reviewed abstracts. These materials present and discuss the studies of modern aspects of experimental and theoretical physics at low and ultralow temperatures, including electronic properties of conducting and superconducting systems, magnetism and magnetic materials, optics, photonics and optical spectroscopy, quantum liquids and quantum crystals, cryocrystals, nanophysics and nanotechnologies, biophysics and physics of macromolecules, materials science, theory of condensed matter physics, technological peculiarities of the instrumentation for physical experiments, and other related fields. The conference proceeding is published as a printed edition. All rights reserved. Editorial board: Sergiy Gnatchenko Gennadiy Grechnev Editor: Olena Vatazhuk Design: Anton Klimkin Layout: Nina Gamayunova ISBN B. Verkin Institute for Low Temperature Physics and Engineering UDK NAS of Ukraine BBK

5 Organizers and Scientific Committee 3 Program Committee Chairman: Prof. Sergiy Gnatchenko, Full Member of NASU, ILTPE NASU (Kharkiv, Ukraine) Vice-chairman: Prof. Gennadiy Grechnev, ILTPE NASU (Kharkiv, Ukraine) Dr. Viktor Chabanenko, DonFTI NASU (Kyiv, Ukraine) Prof. Oleksandr Dolbin, ILTPE NASU (Kharkiv, Ukraine) Dr. Mykola Glushchuk, ILTPE NASU (Kharkiv, Ukraine) Prof. Andrzej Jezowski, Institute of Low Temperature and Structure Research PAS (Wroclaw, Poland) Dr. Oleksandr Kalinenko, ILTPE NASU (Kharkiv, Ukraine) Dr. Gennadii Kamarchuk, ILTPE NASU (Kharkiv, Ukraine) Prof. Viktor Karachevtsev, Corresponding Member of NASU, ILTPE NASU (Kharkiv, Ukraine) Prof. Mykola Kharchenko, Full Member of NASU, ILTPE NASU (Kharkiv, Ukraine) Prof. Yuriy Kolesnichenko, ILTPE NASU (Kharkiv, Ukraine) Dr. Oleksandr Kordyuk, Corresponding member of NASU, IMP NASU (Kyiv, Ukraine) Prof. Ilya Krive, ILTPE NASU (Kharkiv, Ukraine) Dr. Volodymyr Maidanov, ILTPE NASU (Kharkiv, Ukraine) Prof. Yuriy Naidyuk, ILTPE NASU (Kharkiv, Ukraine) Prof. Vasyliy Natsik, ILTPE NASU (Kharkiv, Ukraine) Dr. Anatoliy Negriyko, Corresponding Member of NASU, Institute of Physics NASU (Kyiv, Ukraine) Prof. Oleksandr Omelyanchouk, Corresponding Member of NASU, ILTPE NASU (Kharkiv, Ukraine) Dr. Pavlo Pal-Val, ILTPE NASU (Kharkiv, Ukraine) Prof. Leonid Pastur, Full Member of NASU, ILTPE NASU (Kharkiv, Ukraine) Prof. Eduard Rudavskii, Corresponding Member of NASU, ILTPE NASU (Kharkiv, Ukraine) Prof. Elena Savchenko, ILTPE NASU (Kharkiv, Ukraine) Dr. Sergiy Shevchenko, ILTPE NASU (Kharkiv, Ukraine) Dr. Svyatoslav Sokolov, ILTPE NASU (Kharkiv, Ukraine) Prof. Mykhailo Strzhemechny, Corresponding Member of NASU, ILTPE NASU (Kharkiv, Ukraine) Prof. Andrzej Szewczyk, Institute of Physics PAS (Warsaw, Poland) Prof. Yevgen Syrkin, ILTPE NASU (Kharkiv, Ukraine) Prof. Alexander Vasiliev, Moscow State University (Moscow, Russia) Organizing Committee Chairman: Olena Vatazhuk Vice-chairman: Nataliia Mysko-Krutik Secretary: Anastasiya Lyogenkaya Treasurer: Marina Kolodyazhnaya Accommodation questions: Maksym Barabashko Organizing Committee members: Razet Basnukaeva Nina Gamayunova Vusal Geidarov Anna Herus Olga Ilinskaya Valentin Koverya Denis Laptev Volodymur Meleshko Eugene Petrenko Sergii Poperezhai Yuriy Shapovalov Eugenia Usenko

6

7 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 5 CONFERENCE PROGRAM MONDAY, 3 JUNE 8:00-9:30 Registration CONFERENCE HALL PLENARY LECTURES OF INVITED SPEAKERS Chair Olena Vatazhuk 9:30-9:45 BORIS VERKIN, PHYSICIST AND FOUNDER OF THE INSTITUTE FOR LOW TEMPERATURE PHYSICS AND ENGINEERING 29 G.E. Grechnev B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 9:45-10:25 PROBLEMS OF METHANE EXPLOSION AND BLAST ENERGY SUPPRESSION IN COAL MINES 32 M. Chikhradze 1,2, E. Mataradze 1, K. Tavlalashvili 1, G. Janikashvili 1 1 G.Tsulukidze Mining Institute, Tbilisi, Georgia, 2 Georgian Technical University, Tbilisi, Georgia 10:25-11:05 OPTICAL SPECTROSCOPY OF EXCITONS WITH SPATIALLY SEPARATED ELECTRONS AND HOLES IN NANOHETEROSTRUCTURES WITH SEMICONDUCTOR AND DIELECTRIC QUANTUM DOTS 41 S.I. Pokutnyi Chuiko Institute of Surface Chemistry of NASU, Kyiv, Ukraine 11:05-11:25 General Photo and Coffee Break CONFERENCE HALL NANOPHYSICS AND NANOTECHNOLOGIES Chair Maksym Barabashko 11:25-11:45 THERMAL TRANSPORT IN MOLECULAR DISORDERED CRYSTALS WITH LONG RANGE ORDER 103 D. Szewczyk Institute of Low Temperature and Structure Research PAS, Wrocław, Poland 11:45-12:00 STRUCTURAL FEATURES OF POINT-CONTACT SENSORS BASED ON TETRACYANOQUINODIMETHANE COMPOUNDS 104 D.O. Harbuz 1,2, A.P. Konotop 2, V.A. Gudimenko 2, А.P. Pospelov 1, G.V.Kamarchuk 2 1 National Technical University Kharkiv Polytechnic Institute, Kharkiv, Ukraine 2 B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 12:00-12:20 NOVEL PHENOMENA IN TWO-DIMENSIONAL MATERIALS: ELECTRICAL CONTROL OF INTERLAYER EXCITON DYNAMICS AND SIGNATURES OF SUPERCONDUCTIVITY IN ATOMICALLY THIN TWISTED HETEROSTRUCTURES 105 K. Pistunova Department of Physics, Stanford University, Stanford, California, USA

8 6 Conference Program 12:20-12:35 HIGHLY SELECTIVE NANODEVICES BASED ON CONDUCTANCE QUANTIZATION OF DENDRITIC POINT CONTACTS IN GASES AND LIQUID MEDIA 106 A.O. Herus 1, A.V. Savytskyi 1, А.P. Pospelov 2, Yu.S. Doronin 1, V.L. Vakula 1, G.V. Kamarchuk 1 1 B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Department of Physical Chemistry, National Technical University Kharkiv Polytechnic Institute, Kharkiv, Ukraine 12:35-12:50 ELECTRICAL RELAXATION PROCESSES AND THEIR PHASE PORTRAITS IN NANOSYSTEMS 107 D.A. Dolhopolova 1, V.A. Lykah 2, E.S. Syrkin 3 1 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine 2 National Technical University "Kharkiv Polytechnic Institute", Kharkiv, Ukraine 3 B.Verkin Institute for Low Temperature Physics and Engineering of NASU,Kharkiv, Ukraine 12:50-13:05 CALORIMETRIC STUDIES OF MWCNTs 108 M.S. Barabashko 1, D. Szewczyk 2, M.I. Bagatskii 1, V.V. Sumarokov 1, A. Jeżowski 2, V.L. Kuznetsov 3,4, S.I. Moseenkov 3, A.N. Ponomarev 5 1 B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 W. Trzebiatowski Institute of Low Temperature and Structure Research PAS, Wroclaw, Poland 3 Boreskov Institute of Catalysis, Novosibirsk, Russia 4 National Research Tomsk Polytechnic University, Tomsk, Russia 5 Institute of Strength Physics and Materials Science of SB RAS, Tomsk, Russia 13:05-14:00 Time for Lunch CONFERENCE HALL PLENARY LECTURES OF INVITED SPEAKERS Chair Olena Vatazhuk 14:00-14:40 HYDROGEN STORAGE IN METALLIC MATERIALS ON BASIS OF MAGNESIUM 37 L. Kral 1, J. Cermak 1,2 1 Institute of Physics of Material, AS CR, Brno, Czech Republic 2 CEITEC-Institute of Physics of Materials, AS CR, Brno, Czech Republic 14:40-15:20 LASER DRIVEN ION ACCELERATION FROM A CRYOGENIC HYDROGEN RIBBON 31 T.V. Chagovets Institute of Physics AS CR, ELI-Beamlines Project, Prague, Czech Republic CONFERENCE HALL MATERIALS SCIENCE Chair Olena Vatazhuk 15:20-15:35 MODELLING OF INTERACTION BETWEEN BASAL STACKING FAULTS AND TWIN BOUNDARIES IN MAGNESIUM 133 A. Ostapovets 1, A. Serra 2, R.C. Pond 3 1 Central European Institute of Technology - Institute of Physics of Materials (CEITEC IPM), AS CR, Brno, Czech Republic 2 Department of Civil & Environmental Engineering, Universitat Politecnica de Catalunya, Barcelona, Spain 3 College of Engineering, Mathematics and Physical Sciences, University of Exeter, United Kingdom

9 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 7 15:35-15:50 STRUCTURAL TRANSITIONS IN ORGANIC CRYSTALS 134 E.N. Trotskiy 1, V.A. Lykah 2, E.S. Syrkin 3 1 V. N. Karazin Kharkiv National University, Kharkiv, Ukraine 2 National Engineering University Kharkiv Polytechnic Institute, Kharkiv, Ukraine 3 B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 15:50-16:05 THE EFFECT OF NANOSCALE GRAIN SIZE ON THE STRAIN RATE SENSITIVITY AND ACTIVATION VOLUME IN TITANIUM AT LOW TEMPERATURES 135 R.V. Smolianets, V.A Moskalenko B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 16:05-16:20 INFLUENCE OF GRAIN SIZE ON TWINNING DURING LOW TEMPERATURE PLASTIC DEFORMATION OF AZ31 ALLOY 136 P.A. Zabrodin B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 16:20-16:35 INVESTIGATION OF THE ACOUSTIC PROPERTIES OF NANOSTRUCTURED MATERIALS AT LOW TEMPERATURES 137 O.M. Vatazhuk B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine CONFERENCE HALL TECHNOLOGIES AND INSTRUMENTATION FOR PHYSICAL EXPERIMENTS Chair Olena Vatazhuk 16:35-16:50 SCANNING METHOD FOR DETERMINING THE QUALITY OF THE LENS SURFACE 167 O.O. Fomin Kharkiv National University of Radio Electronics, Kharkiv, 61166, Ukraine 16:50-18:00 POSTER SESSION I 18:00-19:30 KHARKIV-CITY WALKING TOUR

10 8 Conference Program TUESDAY, 4 JUNE CONFERENCE HALL PLENARY LECTURES OF INVITED SPEAKERS Chair Valentin Koverya 9:30-10:10 UNCONVENTIONAL MAGNONICS: FROM NANO-OPTICS TO SUPERCONDUCTIVITY 33 O.V. Dobrovolskiy Physikalisches Institut Goethe University, Frankfurt am Main, Germany 10:10-10:50 ELECTRON-PHONON COOLING POWER IN ANDERSON INSULATORS 34 M.V. Feigel'man 1, V.E. Kravtsov 2,1 1 L.D.Landau Institute for Theoretical Physics., Chernogolovka, Moscow region, Russia 2 International Center for Theoretical Physics, Trieste, Italy 10:50-11:05 Coffee Break CONFERENCE HALL ELECTRONIC PROPERTIES OF CONDUCTING AND SUPERCONDUCTING SYSTEMS Chair Valentin Koverya 11:05-11:20 FEATURES OF THE EXCESS CONDUCTIVITY BEHAVIOR IN A MAGNETIC SUPERCONDUCTOR Dy 0.6 Y 0.4 Rh 3.85 Ru 0.15 B 4 47 A.L. Solovjov, A.V. Terekhov, E.V. Petrenko, L.V. Omelchenko B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 11:20-11:35 LOCALIZED JOSEPHSON PLASMA WAVES IN A PLATE OF LAYERED SUPERCONDUCTOR IN THE PRESENCE OF А DC MAGNETIC FIELD 48 N. Kvitka 1, T. Rokhmanova 1,2, S.S. Apostolov 1,2, V.A. Yampol skii 1,2 1 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine 2 A.Ya. Usikov Institute for Radiophysics and Electronics NASU, Kharkiv, Ukraine 11:35-11:50 FIRST OBSERVATION OF HYPERFINE LEVEL ANTICROSSINGS IN OPTICAL SPECTRA OF A CRYSTAL 49 K.N. Boldyrev, M.N. Popova Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow, Russian Federation 11:50-12:05 SPIN WAVE EIGENMODES IN PERPENDICULARLY MAGNETIZED SUBMICRON TRIANGULAR DOTS 68 Y.I. Kharlan, E.V. Tartakovskaya, P.V. Bondarenko, O.Y. Saliuk, V.O. Golub Institute of Magnetism of NASU and MES of Ukraine, Kyiv, Ukraine 12:05-12:20 INFLUENCE OF THE COULOMB INTERACTION ON THE LONDON PENETRATION DEPTH IN AN ENSEMBLE OF SPIN POLARONS IN CUPRATE HTSCS 51 K.K. Komarov 1, D.M. Dzebisashvili 1,2 1 Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk, Russia 2 Reshetnev Siberian State University of Science and Technology, Krasnoyarsk, Russia 12:20-12:35 THREE SPECTROSCOPY REGIMES OF TWO-LEVEL SYSTEM 52 D.S. Karpov 1,2, S.N. Shevchenko 1,3, U. Hübner 2, E. Il'ichev 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Leibniz-Institut für Photonische Technologien, Jena, Germany 3 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine

11 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 9 12:35-12:50 PARACONDUCTIVITY OF PSEUDOGAPPED SUPERCONDUCTORS 53 I. Poboiko 1,2,3,4, M. Feigel man 3,2 1 Skolkovo Institute of Science and Technology, Moscow, Russia 2 National Research University Higher School of Economics, Moscow, Russia 3 L. D. Landau Institute for Theoretical Physics, Chernogolovka, Moscow region, Russia 4 Condensed Matter Physics Laboratory, National Research University Higher School of Economics, Moscow, Russia 12:50-13:05 EQUILIBRATION AND THERMALIZATION IN THE PERTURBED 1D XXZ MODEL 159 P. Jaeger 1,2, A. Klümper 2, J. Sirker 1 1 University of Manitoba, Department of Physics and Astronomy, Winnipeg, MB, Canada 2 Bergische Universität Wuppertal, Fachbereich C - Fachgruppe Physik, Wuppertal, Germany 13:05-13:20 NONLINEAR DYNAMICS OF THE SPIN CHAIN WITH LONG-RANGE INTERACTION IN THE CONTINUUM LIMIT 70 P.V. Bondarenko, B.A. Ivanov Institute of Magnetism of NASU and MES of Ukraine, Kyiv, Ukraine 13:20-14:00 Time for Lunch CONFERENCE HALL PLENARY LECTURES OF INVITED SPEAKERS Chair Nataliia Mysko-Krutik 14:00-14:40 LOGARITHMIC FLUIDS 43 K.G. Zloshchastiev Institute of Systems Science, Durban University of Technology, Durban, South Africa 14:40-15:20 APPLICATION OF OPTICAL ANGULAR MOMENTUM AND QUANTUM ENTANGLEMENTS IN BIOMEDICAL TISSUE DIAGNOSTICS 40 I. Meglinski Laboratory of Opto-Electronics and Measurement Techniques, University of Oulu, Oulu, Finland CONFERENCE HALL BIOPHYSICS AND PHYSICS OF MACROMOLECULES Chair Nataliia Mysko-Krutik 15:20-15:35 GRAPHENE SINGLE-WALLED CARBON NANOTUBE NANOSTRUCTURES: MOLECULAR DYNAMICS MODELLING 123 M.V. Karachevtsev B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 15:35-15:50 THE POSSIBILITY OF BLOCKING THE PROCESS OF DNA BASE PAIRS OPENING BY HYDROGEN PEROXIDE 124 O.O. Zdorevskyi, S.N. Volkov Bogolyubov Institute for Theoretical Physics, Kyiv, Ukraine 15:50-16:05 COMPOSITE FILMS OF SINGLE-WALLED CARBON NANOTUBES WITH GRAPHENE OXIDE: TEMPERATURE DEPENDENCE OF ELECTRONIC CONDUCTIVITY 125 N.V. Kurnosov, V.A. Karachevtsev B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 16:05-16:20 CHARACTERIZATION OF SWNT-GO NANOHYBRIDS 126 A.Yu. Glamazda 1,2, S.G. Stepanian 1, M.V. Karachevtsev 1, A.M. Plokhotnichenko 1, V.A. Karachevtsev 1 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine

12 10 Conference Program CONFERENCE HALL QUANTUM LIQUIDS AND QUANTUM CRYSTALS, CRYOCRYSTALS Chair Nataliia Mysko-Krutik 16:20-16:35 STRUCTURAL STUDIES OF CH 4 -N 2, N 2 -Kr, Ar-Kr CRYOALLOYS 91 N. Mysko-Krutik, A. Solodovnik B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 16:35-16:50 ON THE ONE THERMOMAGNETIC EFFECT IN SUPERFLUID SYSTEMS 92 A.M. Konstantinov, S.I. Shevchenko B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 16:50-17:05 ELECTRONICALLY-STIMULATED DELAYED DESORPTION OF PARTICLES FROM SOLID METHANE AND SOLID ARGON DOPED WITH METHANE 93 I.V. Khyzhniy, E.V. Savchenko, S.A. Uyutnov, M.A. Bludov B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 17:05-18:00 POSTER SESSION II 19:30-23:00 WELCOME PARTY WEDNESDAY, 5 JUNE 10:00-19:00 MAIN EXCURSION PROGRAM AND PICNIC

13 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 11 THURSDAY, 6 JUNE CONFERENCE HALL PLENARY LECTURES OF INVITED SPEAKERS Chair Marina Kolodyazhnaya 9:30-10:10 CATIONIC SUBSTITUTION vs. MULTIFERROICS PROPERTIES IN METASTABLE PEROVSKITES 35 E. Gilioli 1, D. Delmonte 1, A. Gauzzi 2, F. Mezzadri 1, M. Verseils 3 1 CNR-IMEM, Institute of Materials for Electronic and Magnetism, Parma, Italy 2 IMPMC, Sorbonne Université-CNRS-IRD-MNHN, Paris, France 3 Synchrotron SOLEIL, L Orme des Merisiers, Saint-Aubin, France 10:10-10:50 QUANTUM INFORMATION PROCESING WITH MICROWAVE PHOTONIC STATES IN SUPERCONDUCTING JOSEPHSON CIRCUITS 42 V.S. Shumeiko Dept. Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden 10:50-11:05 Coffee Break CONFERENCE HALL MAGNETISM AND MAGNETIC MATERIALS Chair Marina Kolodyazhnaya 11:05-11:20 MAGNETIC PROPERTIES AND H-T PHASE DIAGRAMM OF TbCr 3 (BO 3 ) 4 65 A. Bludov 1, Yu. Savina 1, M. Kobets 1, V. Khrustalyov 1, V. Savitsky 1, V. Pashchenko 1, T. Zajarniuk 2, M.U. Gutowska 2, A. Szewczyk 2, I. Kolodiy 3, N. Kuzmin 4, V. Mal tsev 4, N. Leonyuk 4 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Institute of Physics, Polish Academy of Sciences, Warsaw, Poland 3 National Science Center «Kharkov Institute of Physics and Technology» Kharkiv, Ukraine 4 Lomonosov Moscow State University, Moscow, Russia 11:20-11:35 MAGNETIC PROPERTIES OF GREIGITE NANOPARTICLES OF DIFFERENT SIZES 66 M. Pashchenko, P. Veverka, O. Kaman, J. Hejtmanek Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic 11:35-11:50 THE INTENSITY OF f - f ELECTRONIC TRANSITIONS IN A CRYSTAL PrFe 3 (BO 3 ) 4 DURING ELECTRON-PHONON INTERACTION 67 K.N. Boldyrev 1, M.N. Popova 1, B.Z. Malkin 2 1 Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow, Russian Federation 2 Kazan Federal University, Kazan, Russian Federation 11:50-12:05 MAGNETIC PROPERTIES OF RCoO 3 COBALTITES (R = La, Pr, Nd, Sm, Eu). EFFECTS OF HYDROSTATIC AND CHEMICAL PRESSURE 50 A.A. Lyogenkaya 1, G.E. Grechnev 1, A.S. Panfilov 1, I.P. Kobzar 1, V.O. Pashchenko 1, L.O. Vasylechko 2, V.M. Hreb 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Lviv Polytechnic National University, Lviv, Ukraine 12:05-12:20 FMR FEATURES OF Fe 3 S 4 NANOPARTICLES AT T = 300K IN COMPARISON WITH LOW TEMPERATURE DATA 69 O. Kravchuk 1, A. Vakula 1,2, M. Pashchenko 3, P. Veverka 3, J. Kuličková 3, O. Kaman 3 1 Kharkiv National University of Radio Electronics, Kharkiv, Ukraine

14 12 Conference Program 2 O.Ya. Usikov Institute for Radiophysics and Electronics of NASU, Kharkiv, Ukraine 3 Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic 12:20-12:35 MAGNETIC RESONANCE AND SHORT-RANGE MAGNETIC ORDER IN ErAl 3 (BO 3 ) 4 CRYSTAL 71 S.N. Poperezhai 1, V.A. Bedarev 1, D.N. Merenkov 1, M.I. Kobets 1, A.A. Zvyagin 1, T. Zajarniuk 2, A. Szewczyk 2, M.U. Gutowska 2, I.A. Gudim 3 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Institute of Physics, Polish Academy of Sciences, Warsaw, Poland 3 Kirensky Institute of Physics, Krasnoyarsk, Russia 12:35-13:00 LAB TOUR 13:00-14:00 Time for Lunch CONFERENCE HALL PLENARY LECTURES OF INVITED SPEAKERS Chair Sergii Poperezhai 14:00-14:40 GRAPHENE AND 2D MATERIALS FOR NEXT GENERATION PHOTONICS, OPTO-ELECTRONICS AND ELECTRONICS 30 A. Baldycheva Centre for Graphene Science & Nano Engineering Science and Technology Group, College of Engineering, Mathematics and Physical Sciences, University of Exeter, UK 14:40-15:20 TAILORING CUSTOM POLARIZATION STATES 38 C. López-Mariscal 1,2 1 Department of Physics and Astronomy, Appalachian State University, Boone, NC, USA 2 Underwater Photonics, Cozumel, Mexico 15:20-15:30 OSA and SPIE Special Coffee Break CONFERENCE HALL OPTICS, PHOTONICS AND OPTICAL SPECTROSCOPY Chair Sergii Poperezhai 15:30-15:45 PHOTOPHYSICS OF HALOGEN SUBSTITUTED ASYMMETRICAL PORPHYCENES AT THE LIQUID NITROGEN TEMPERATURE 79 A.Yu. Kharchenko, A. Listkowski, J. Waluk Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland 15:45-16:00 OPTICAL SPECTROSCOPY AND POLARIZED LIGHT STUDY OF Co- BASED LAYER DOUBLE HYDROXIDES 80 I.M. Lukienko 1, R.Yu. Babkin 2, Yu.G. Pashkevich 2, Yu.M. Kharchenko 1, D. Wulferding 3, P. Lemmens 3,4, D.E.L. Vieira 5, A.N. Salak 5 1 В.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 O. Galkin Donetsk Institute for Physics and Engineering of NASU, Kyiv, Ukraine 3 Laboratory for Emerging Nanometrology (LENA), TU Braunschweig, Braunschweig, Germany 4 Institute for Condensed Matter Physics, TU Braunschweig, Braunschweig, Germany 5 CICECO-Aveiro Institute of Materials, Department of Materials and Ceramics Engineering, University of Aveiro, Aveiro, Portugal 16:00-16:15 LASER STIMULATED WHITE EMISSION PROCESSES IN TRANSPARENT Cr 3+,Cr 4+,Ca 2+ :YAG CERAMICS 81 M. Chaika 1, R. Tomala 1, O.M. Vovk 2, R.P. Yavetskiy 2, W. Strek 1 1 Institute for Low Temperatures and Structure Research PAS, Wroclaw, Poland

15 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 13 2 STC Institute for Single Crystals of NASU, Kharkiv, Ukraine 16:15-16:30 OPTICAL RESPONSE OF HOLLOW GOLD NANOPARTICLES 82 L.N. Illyashenko 2, N.P. Stognii 1, O.G. Nerukh 1 1 Kharkiv National University of Radio Electronics, Kharkiv, Ukraine 2 O.Ya. Usikov Institute for Radiophysics and Electronics of NASU, Kharkiv, Ukraine 16:30-16:45 RESONANT ABSORPTION OF ELECTROMAGNETIC WAVES ACCOMPANIED BY EXCITATION OF LOCALIZED MODES WITH ANOMALOUS DISPERSION IN LAYERED SUPERCONDUCTORS 83 S.S. Apostolov 1,2, M.V. Mazanov 2, Z.A. Maizelis 1,2, N.M. Makarov 3, A.A. Shmat'ko 2, V.A. Yampol'skii 1,2 1 O.Ya. Usikov Institute for Radiophysics and Electronics NASU, Kharkiv, Ukraine 2 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine 3 Benemérita Universidad Autónoma de Puebla, Puebla, Pue.México 16:45-17:00 NUMERICAL SIMULATION OF EELS SPECTRA OF PLASMONIC NANODIMERS ACCOUNTING FOR SPATIAL DISPERSION EFFECTS WITH THE DISCRETE SOURCES METHOD 84 I.V. Lopushenko M.V. Lomonosov Moscow State University, Faculty of Physics, Moscow, Russia STUDENT CLUB (OTAKARA YAROSHA 11b) IAPS ROUND TABLE Chair Nina Gamayunova 18:00-19:00 IAPS LC Kharkiv, the first student branch of the International association of physics students (IAPS) in Ukraine, presents the event for young scientists devoted to the 1 st anniversary of IAPS LC Kharkiv with invited lecture from Dr. Tetiana Rokhmanova, Active IAPS member in O.Ya. Usikov Institute for Radiophysics and Electronics of NASU, Kharkiv, Ukraine Discover physics world with IAPS. Experience of Indivifual membership 19:00-19:30 IAPS Special Coffee Break STUDENT CLUB (OTAKARA YAROSHA 11b) OSA & SPIE YSW Chair Nataliia Mysko-Krutik 19:30-20:30 ILTPE OSA (The Optical Society) and IRE SPIE (The International Society for Optics and Photonics) Student Chapters is organizing Young Scientists Workshop (YSW) devoted to the failfures in scientific career development. Dr. Mariia Pashchenko Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic The MSCA grant as external opportunities for PostDocs: work, study, collaborate, enjoy Prof. C. López-Mariscal, OSA Travelling Lecturer Department of Physics and Astronomy, Appalachian State University, Boone, NC, USA, and Underwater Photonics, Cozumel, Mexico Ms. Anna Herus, President of ILTPE OSA SC Mr. Volodymyr Meleshko, President of IRE SPIE SC

16 14 Conference Program FRIDAY, 7 JUNE CONFERENCE HALL PLENARY LECTURES OF INVITED SPEAKERS Chair Denis Laptev 9:30-10:10 QUANTUM ANALOGUE OF ENERGY EQUIPARTITION THEOREM 39 P. Bialas, J. Spiechowicz, J. Łuczka Institute of Physics and Silesian Center for Education and Interdisciplinary Research, University of Silesia, Chorzów, Poland 10:10-10:50 PHASE TRANSITIONS IN NEW 2D FRUSTRATED MAGNETS Cu 3 R(SeO 3 ) 2 O 2 Cl STUDIED BY OPTICAL SPECTROSCOPY 36 S.A. Klimin Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow, Russia 10:50-11:20 Coffee Break CONFERENCE HALL THEORY OF CONDENSED MATTER PHYSICS Chair Denis Laptev 11:20-11:55 LOW-TEMPERATURE INSTABILITY IN QUANTUM DETECTION OF CHARGE-QUBIT DECOHERENCE BY MEANS OF ONE-DIMENSIONAL TUNNEL JUNCTIONS: EXACT SUMMATION THEOREM FOR REAL- TIME PROPAGATORS 149 G.A. Skorobagatko Institute for Condensed Matter Physics of NASU, Lviv, Ukraine 11:55-12:10 FEATURES OF MAGNETIC ORDERING AND NON-EQUILIBRIUM PROCESSES IN MAGNETICS WITH SPIN S=3/2 AND SU(4) SYMMETRY OF THE EXCHANGE INTERACTION 150 A.V. Glushchenko, M.Y. Kovalevsky Kharkiv Institute of Physics and Technology, Kharkiv, Ukraine 12:10-12:25 NUMERICAL MODELING OF THE DYNAMICS OF PALLADIUM AND NICKEL CLUSTERS AND NANOPARTICLES 151 D.V. Laptev 1, D. Terentyev 2, V.I. Dubinko 3, K. Irwin 4 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 NSC Kharkov Institute of Physics and Technology, Kharkiv, Ukraine 3 SCK CEN, Nuclear Materials Science Institute, Boeretang, Mol, Belgium 4 Quantum Gravity Research, Los Angeles, USA 12:25-12:40 TIME OF LANDAU-ZENER-STÜCKELBERG-MAJORANA TRANSITION 152 O.V. Ivakhnenko 1,2,3, S.N. Shevchenko 1,2, F. Nori 3,4 1 B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine 3 Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wakoshi, Saitama, Japan 4 Physics Department, University of Michigan, Ann Arbor, MI, USA 12:40-12:55 SLOWING OF ELECTROMAGNETIC PULSES IN THE PROXIMITY OF PHASE TRANSITION TO BOSE-EINSTEIN CONDENSATE IN ULTRACOLD ATOMIC GASES 153 D.M. Raspopova 1, A.G. Sotnikov 2 1 V. N. Karazin Kharkiv National University, Kharkiv, Ukraine 2 Akhiezer Institute for Theoretical Physics, NSC KIPT, Kharkiv, Ukraine

17 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 15 12:55-13:10 THE INFLUENCE OF COULOMB CORRELATIONS ON MAGNETIC SHUTTLING 154 O.A. Illinskaya 1, I.V. Krive 1,2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Physical Department, V.N. Karazin National University, Kharkiv, Ukraine 13:10-14:00 Time for Lunch CONFERENCE HALL THEORY OF CONDENSED MATTER PHYSICS Chair Denis Laptev 14:00-14:15 EFFECTS OF COULOMB INTERACTION AND FRANCK-CONDON BLOCKADE IN TUNNELING OF SPIN-POLARIZED ELECTRONS IN A MOLECULAR TRANSISTOR 155 A.D. Shkop 1, O.M. Bahrova 1, I.V. Krive 1,2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Department of Theoretical Physics named by academician I.M. Lifshits, V. Karazin National University, Kharkiv, Ukraine 14:15-14:30 DYNAMICS IN THE GRAVITATIONAL FIELD OF A TORUS WITH A CENTRAL MASS 156 L.D. Manchenko 1, E.Yu. Bannikova 1,2 1 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine 2 Institute of Radio Astronomy, NASU, Kharkiv, Ukraine 14:30-14:45 ORBITAL ORDERING OF ULTRACOLD FERMIONIC MIXTURES IN OPTICAL LATTICES 157 A.G. Sotnikov Akhiezer Institute for Theoretical Physics, NSC KIPT, Kharkiv, Ukraine 14:45-15:00 PLASMA AND ORDER PARAMETER COLLECTIVE OSCILLATIONS IN GRAPHENE COUNTERFLOW SUPERCONDUCTORS 158 K.V. Germash 1, D.V. Fil 1,2 1 Institute for Single Crystals of NASU, Kharkiv, Ukraine 2 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine 15:00-16:00 CONCERT OF CLASSICAL MUSIC 16:00-16:15 CLOSING

18 16 Conference Program POSTER SESSION I MONDAY, 3 JUNE 16:50-18:00 NANOPHYSICS AND NANOTECHNOLOGIES P1 P2 P3 P4 P5 P6 P7 EFFECT OF COLD PLASMA TREATMENT ON HYDROGEN SORPTION BY GRAPHENE OXIDE R.M. Basnukaeva 1, A.V. Dolbin 1, V.B. Eselson 1, V.G. Gavrilko 1, N.A. Vinnikov 1, M.V. Khlistuck 1, S. Cherednychenko 2 1 B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 National Technical University «Kharkiv Polytechnic Institute», Kharkiv,Ukraine HYDROGEN SORPTION IN HYBRID NANOSTRUCTURED CARBON/PALLADIUM MATERIALS AT LOW TEMPERATURES D.O. Gritsay 1, R.M. Basnukaeva 2, A.V. Dolbin 2, V.B. Eselson 2, V.G. Gavrilko 2, N.A. Vinnikov 2, M.V. Khlistuck 2, V.I. Dubinko 3 1 National Technical University «Kharkiv Polytechnic Institute», Kharkiv, Ukraine 2 B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 3 National Science Center Kharkov Institute of Physics and Technology, Kharkiv, Ukraine DEPENDENCE OF TUNNEL RESISTANCE FOR POWDERS OF COMPACTED CHROMIUM DIOXIDE NANOPARTICLES ON THICKNESS AND TYPE OF DIELECTRIC SHELLS V.A. Horielyi, N.V. Dalakova, E.Yu. Beliayev B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine REDOX ACTIVITY OF ORTHOVANADATE NPs DOPED WITH EUROPIUM IONS LnVO 4 :Eu 3+ (Ln = Gd, Y, La) K.A. Hubenko, S. Yefimova, P. Maksimchuk, N. Kavok, V. Klochkov Institute for Scintillation Materials of NASU, Kharkiv, Ukraine DELTA-DOPED QUANTUM WELLS AND BACKGROUND IMPURITIES Ya. Kotov 1, R. Demediuk 1, V. Akimov 2, C.A. Duque 3, A. Tiutiunnyk 4, D. Laroze 4, D. Sushenko 1, V. Tulupenko 1, O. Fomina 1 1 Donbass State Engineering Academy, Kramatorsk, Ukraine 2 Facultad de Ciencias Básicas, Universidad de Medellín, Medellín, Colombia 3 Grupo de Materia Condensada-UdeA, Universidad de Antioquia, Medellín, Colombia 4 Instituto de Alta Investigación, CEDENNA, Universidad de Tarapacá, Arica, Chile MAGNETORESISTANCE OF NANOGRAPHITE PARTICLES WITH DIFFERENT STRUCTURE T. Len 1, I. Ovsiienko 1, O. Syvolozhskyi 1, O. Marinin 1, I. Mirzoiev 2, I. Berkutov 2,3, V. Andrievskii 2, D. Shpylka 1, L. Matzui 1 1 Taras Shevchenko National University of Kyiv, Ukraine 2 B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 3 Department of Physics, North Carolina State University, Raleigh, NC, USA MOLECULAR PHOTODIODE AS A LIGHT EMITTER V.O. Leonov, E.G. Petrov, Ye.V. Shevchenko Bogolyubov Institute for Theoretical Physics of NASU, Kyiv, Ukraine

19 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 17 P8 P9 P10 PECULIARITIES OF PHONON EXTENSION IN GRAPHENE NANOSTRUCTURES K.A. Minakova 1, I.A. Gospodarev 2, S.B. Feodosyev 2, E.S. Syrkin 2 1 National Technical University «Kharkiv Polytechnic Institute», Kharkiv, Ukraine 2 B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine INFLUENCE OF THE HYDROGEN INTERCALATION ON THE STRUCTURAL PROPERTIES OF FeTe 0,65 Se 0,35 SINGLE CRYSTAL A.I. Prokhvatilov, S.I. Bondarenko, V.V. Meleshko, V.P. Koverya B. Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine PHASE STATE, CRYSTAL STRUCTURE OF THIN FILMS OF Fe x Со 1-х ALLOY AND THREE-LAYER STRUCTURES BASED ON IT WITH A Cu LAYER D.I. Saltykov, Yu.O. Shkurdoda Sumy State University, Sumy, Ukraine MATERIALS SCIENCE P11 P12 P13 P14 P15 P16 LARGELY ENHANCED MECHANICAL PROPERTIES OF GRAPHENE OXIDE/POLYESTER RESIN NANOCOMPOSITES H.V. Rusakova 1, L.S. Fomenko 1, S.V. Lubenets 1, A.V. Dolbin 1, N.A. Vinnikov 1, R.M. Basnukaeva 1, M.V. Khlistyuck 1, A.V. Blyznyuk 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 National Technical University "Kharkiv Polytechnic Institute", Kharkiv, Ukraine POROUS SODIUM-RICH CALCIUM PHOSPHATE CERAMICS N. Mielnik 1, A. Goncharenko 1, Z. Zyman 1 1 V.N.Karazin Kharkiv NationalUniversity, Kharkiv, Ukraine KINETIC AND MECHANICAL PROPERTIES OF THE HIGH-ENTROPY ALLOY Аl 0.5 CoCuCrNiFe AT LOW TEMPERATURES E.S. Savchuk, V.A. Frolov, V.I. Sokolenko, M.A. Tikhonovskij, E.V. Karaseva National Science Center Kharkov Institute of Physics and Technology, Kharkiv, Ukraine MECHANICAL AND DISSIPTIVE PROPERTIES OF VT6 ALLOY WITH NANOMETER SCALE STRUCTURES OBTAINED BY CRYODEFORMATION METHODS N.A. Shulgin, V.I. Sokolenko, A.V.Mats, V.S. Okovit, P.A. Khaimovich National Science Center Kharkiv Institute of Physics & Technology of NASU,Kharkiv, Ukraine EFFECT OF CRYO-DEFORMATION BY REPETITIVE UPSETTING EXTRUSION ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF CoCrFeMnNi HIGH-ENTROPY ALLOY A.V. Levenets, A.S. Kalchenko, M.A. Tikhonovsky, P.A. Khaimovich National Science Center Kharkov Institute of Physics and Technology, Kharkiv, Ukraine MECHANICAL PROPERTIES AND MICROSTRUCTURE OF HIGH ENTROPY ALLOY CoCrFeNiMn AFTER HIGH PRESSURE TORSION AT 300 AND 77 K Yu.O. Shapovalov 1, E.D. Tabachnikova 1, A.V. Podolskiy 1, M. Zehetbauer 2, E. Schafler 2, M.A. Tikhonovskiy 3 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 University of Vienna, Vienna, Austria 3 National Science Center Kharkov Institute of Physics and Technology NASU, Kharkiv, Ukraine

20 18 Conference Program P17 P18 DISLOCATION-KINETIC APPROACH TO TENSILE STRESS-STRAIN CURVE CALCULATION FOR PLATE SPECIMENS OF TWO- DIMENTIONAL POLYCRYSTALS OF HIGH PURITY METALS Ye.V. Ftomov Physics Department, V.N.Karazin Kharkiv National University, Kharkiv, Ukraine NEAR ORDER IN THIN FILMS BY PM-A V.G. Geidarov 1, I.S. Braude 1, N.N. Galtsov 1, N.A. Aksenova 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Ukrainian State University of Railway Transport, Kharkiv, Ukraine THEORY OF CONDENSED MATTER PHYSICS P19 P20 P21 P22 P23 EFFECTS OF FRUSTRATION IN QUANTUM HEISENBERG ANTIFERROMAGNETS ON BILAYER LATTICES V.Ya. Baliha Institute for Condensed Matter Physics of NASU, Lviv, Ukraine CHARGE AND SPIN CORRELATIONS IN LOW-DIMENSIONAL DOPED QUANTUM ANTIFERROMAGNETS Suraka Bhattacharjee 1, Ranjan Chaudhury 2a,b 1,2a SN Bose National Centre for Basic Sciences,Saltlake, Kolkata, India 2b Ramkrishna Mission Vivekananda Educational and Research Institute, Belur, India THE FALICOV-KIMBALL MODEL WITH CORRELATED HOPPING: X- RAY PHOTOEMISSION SPECTROSCOPY D.A. Dobushovskyi Institute for Condensed Matter Physics of NASU, Lviv, Ukraine COLLECTIVE SCATTERING OF LANGMUIR-GAS STREAM BY IMPURITY CLUSTERS: SHOCK-WAVE ENHANCEMENT BY DISORDER O.V. Kliushnychenko, S.P. Lukyanets Institute of Physics of NASU, Kyiv, Ukraine ONE-DIMENSIONAL HEISENBERG ANTIFERROMAGNETS WITH ALMOST LOCALIZED MAGNONS AT HIGH MAGNETIC FIELDS AND LOW TEMPERATURES O.M. Krupnitska Institute for Condensed Matter Physics of NASU, Lviv, Ukraine TECHNOLOGIES AND INSTRUMENTATION FOR PHYSICAL EXPERIMENTS P24 P25 LONG-WAVELENGTH INFRARED CRYOGENIC FILTERS P.V. Kiporenko 1, A.P. Ovcharenko 1, D.T.N. Tranh 1,2, N.L. Dyakonenko 3, E.Yu. Gordiyenko 4, Yu.V. Fomenko 4 1 V.N. Karazin Kharkov National University, Kharkov, Ukraine 2 Hochiminh city university of technology, Ho Chi Minh City 3 National Technical University Kharkiv Polytechnic Institute, Kharkiv,Ukraine 4 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine ARTIFICIAL NEURAL NETWORK AS AN INSTRUMENT FOR THE COMPLEX RELAXATION SPECTRA DECOMPOSITION I.V. Lishchuk, V.V. Ilchenko, V.Y. Opylat, S.V. Tyshchenko Institute of High Technologies, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine

21 P26 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine AUTOMATION SYSTEM FOR SEMICONDUCTOR DEVICES PARAMETERS MEASUREMENT R.V. Zaitsev, M.V. Kirichenko, D.S. Prokopenko, M.G. Khrypunov K.A. Minakova, G.A. Drozdova National Technical University «Kharkiv Polytechnic Institute», Kharkiv, Ukraine

22 20 Conference Program POSTER SESSION II TUESDAY, 4 JUNE 17:05-18:00 ELECTRONIC PROPERTIES OF CONDUCTING AND SUPERCONDUCTING SYSTEMS P1 P2 P3 P4 P5 P6 P7 P8 ULTRAFAST VORTEX DYNAMICS IN SUPERCONDUCTORS: FROM LOCAL INSTABILITY TO SUPERSONIC VELOCITIES V.M. Bevz 1, A.I. Bezuglyj 1, V.A. Shklovskij 1, R.V. Vovk 1, E. Begun 2, R. Sachser 2, M. Huth 2, O.V. Dobrovolskiy 1,2 1 Physics Department, V. Karazin National University, Kharkiv, Ukraine 2 Physikalisches Institut Goethe University, Frankfurt am Main, Germany ANISOTROPY AND VACANCY EFFECTS IN ELECTRONIC PROREPTIES OF NbSe 2 & RELATED STRUCTURES I.S. Bondar, S.B. Feodosyev, I.A. Gospodarev, V.A. Sirenko B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine POINT-CONTACT INVESTIGATION OF TOPOLOGICAL INSULATOR SnTe N.V. Gamayunova, O.E. Kvitnitskaya, A.V. Terekhov, Yu.G. Naidyuk B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine SUPERCONDUCTING FLUX QUBIT AND QUTRIT: COMPARISON AND POSSIBLE APPLICATIONS M.E. Holub 1, O.G.Turutanov 2, А.А. Soroka 3, V.Yu. Lyakhno 2, V.I. Shnyrkov 4 1 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine 2 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 3 National Science Center Kharkiv Institute of Physics and Technology, Akhiezer Institute for Theoretical Physics, Kharkiv, Ukraine 4 Kyiv Academic University, Kyiv, Ukraine EFFECT OF JOSEPHSON JUNCTIONS ASYMMETRY ON THE CRITICAL CURRENT OF A QUANTUM INTERFEROMETER V.P. Koverya, S.I. Bondarenko, V.N. Fenchenko, A.V. Krevsun B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine SQUID WITH WEAK LINKS MILLED BY FOCUSED ION BEAM S.I. Bondarenko 1, V.P. Koverya 1, A.V. Krevsun 1, U. Hübner 2, E.V. Il ichev 2, R. Sachser 3, M. Huth 3, O.V. Dobrovolskiy 3 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Leibniz Institute of Photonic Technology, Jena, Germany 3 Physikalisches Institut Goethe University, Frankfurt am Main, Germany SUPPRESSION OF ORDER-DISORDER TRANSITION IN HAFNIUM- DOPED YBaCuO COMPOUNDS S.N. Kamchatnaya 1, Yu.V. Litvinov 2, R.V. Vovk 2, L.A. Kotvitskaya 2 1 Ukrainian State University of Railway Transport, Kharkiv, Ukraine 2 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine DETECTION OF THE CHARACTERISTICS OF THE BUBBLE BOILING REGIME IN HELIUM BY A SUPERCONDUCTING FILM IN A RESISTIVE STATE S. Kruglov, A.S. Pokhila, A.G. Sivakov B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine

23 P9 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine EVOLUTION OF A FOUR-LEVEL QUANTUM SYSTEM M.A. Nakonechnyi 1, A.I. Ryzhov 1,2, S.N. Shevchenko 1,2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 V.N. Karazin Kharkiv National University, Kharkiv, Ukraine QUANTUM LIQUIDS AND QUANTUM CRYSTALS, CRYOCRYSTALS P10 P11 P12 P13 P14 P15 CONCENTRATION AND MOLAR VOLUME DEPENDENCE OF THERMAL CONDUCTIVITY OF RARE GAS SOLIDS SOLUTIONS A.V. Karachevtseva, V.A.Konstantinov, V.V. Sagan, V.P. Revyakin B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine STRUCTURE DETERMINATION OF LOW-TEMPERATURE PHASE OF SOLID MONOSILANE SIH4 USING LENNARD-JONES POTENTIALS. CALCULATION D.E. Hurova 1,2, N.N. Galtsov 2, A.I. Prokhvatilov 2 1 V.N.Karazin KharkivNatsonal University, Kharkiv, Ukraine 2 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine NONLINEAR BEHAVIOR OF THE QUARTZ TUNING FORK IN VACUUM AND He II Kh. Mykhailenko 1, T. Dubchak 2, G. Sheshin 1 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 V. N. Karazin Kharkiv National University, Kharkiv, Ukraine EFFECT OF 3 HE IMPURITY ON DAMPING OF TUNING FORK OSCILLATIONS IN SUPERFLUID HELIUM V.A. Vrakina 1, S.S. Kapuza 1, V.K. Chagovets 1,2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 V. N. Karazin Kharkiv National University, Kharkiv, Ukraine NMR MULTIECHO IN 3 HE ADSORBED BY THE NANOSTRUCTURED SiO 2 MATERIAL MSM-41 А.P. Birchenko 1, Ya.Yu. Fysun 1, N.P. Mikhin 1, A.S. Taran 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 V. N. Karazin Kharkiv National University, Kharkiv, Ukraine LIOUVILLE EQUATION FOR A WEAKLY EXCITED LOW- TEMPERATURE GAS IN A RANDOM ELECTROMAGNETIC FIELD Ye.V. Yedelkina 1, Yu.V. Slyusarenko 1,2 1 Karazin Kharkiv National University, Kharkiv, Ukraine 2 Akhiezer Institute for Theoretical Physics,NSC KIPT, Kharkiv, Ukraine P16 EXPERIMENTAL SETUP FOR STUDY OF SOLID HELIUM FLOW THROUGH A NARROW CAPILLARY D.S. Sedykh, S.P. Rubets, A.S. Neoneta, O.S. Rybalko, V.A. Maidanov B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 100

24 22 Conference Program BIOPHYSICS AND PHYSICS OF MACROMOLECULES P17 P18 P19 P20 INTERACTION OF Zn 2+ IONS WITH SINGLE-STRANDED POLY(C) AND POLY(I) IN A NEUTRAL SOLUTION E.L. Usenko, V.A. Valeev, V.A. Sorokin B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine H-AGGREGATION OF THE NOVEL TRIMETHINE CYANINE DYE AS AN INDICATOR OF INSULIN AMYLOID TRANSFORMATION U.T. Tarabara, K.O. Vus, O.A. Ryzhova, V.M. Trusova V.N. Karazin Kharkiv National University, Kharkiv, Ukraine INTERACTIONS OF BIOGENIC AMINES AND SYNTHETIC QUATERNARY AMMONIUM COMPOUNDS WITH GRAPHENE OXIDE V.G. Zobnina, O.A. Boryak, M.V. Kosevich B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine DIELECTRIC PROPERTIES OF NANOPARTICLE SUSPENSIONS AT LOW TEMPERATURES: A THERMODYNAMIC OF SOLUTION HYDRATION L.V. Batyuk 1, O.M. Morozova 1, N.N. Kizilova 2 1 Kharkiv National Medical University, Kharkiv, Ukraine 2 Warsaw University of Technology, Warsaw, Poland MAGNETISM AND MAGNETIC MATERIALS P21 P22 P23 LOW-TEMPERATURE THERMODYNAMICS OF FINITE SPIN-1/2 XX CHAINS WITH XXZ IMPURITIES O.S. Dzhenzherov, E. V. Ezerskaya V.N.Karazin Kharkiv National University, Dept. of Physics, Kharkiv, Ukraine EXCHANGE BIAS PHENOMENA IN NEW MULTIFERROIC BiFe 0.5 Sc 0.5 O 3 PEROVSKITE A.V. Fedorchenko 1, E.L. Fertman 1, V.A. Desnenko 1, V.V. Shvartsman 2, D.C. Lupascu 2, S. Salamon 3, H. Wende 3, A.I. Vaisburd 4, A. Stanulis 5,6, R. Ramanauskas 5, N.M. Olekhnovich 7, A.V. Pushkarev 7, Yu.V. Radyush 7, D.D. Khalyavin 8, A.N. Salak 9 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Institute for Materials Science & CENIDE, University of Duisburg-Essen, Essen, Germany 3 Faculty of Physics & CENIDE, University of Duisburg-Essen, Duisburg, Germany 4 V. N. Karazin Kharkiv National University, Kharkiv, Ukraine 5 Department of Electrochemical Materials Science CPST, Vilnius, Lithuania 6 Energy Safety Research Institute (ESRI), Swansea University, Swansea, United Kingdom 7 Scientific-Practical Materials Research Centre of NASB, Minsk, Belarus 8 ISIS Facility, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom 9 Department of Materials and Ceramic Engineering, University of Aveiro, Aveiro, Portugal ELASTIC, PIEZO AND MAGNETOELECTRIC PROPERTIES OF HoAl 3 (BO 3 ) 4 M.P. Kolodiazhnaia 1, I.V. Bilych 1, K.R. Zhekov 1, G.A. Zvyagina 1, V.D. Fil 1, I.A. Gudim 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 L.V. Kirensky Institute for Physics, Siberian Branch of RAS, Krasnoyarsk, Russia

25 P24 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine SPIN-WAVE RESONANCES IN INDIVIDUAL CIRCULAR NANOMAGNETS N.R. Vovk 1, S.A. Bunyaev 2, D. Navas 2, P. Gruszecki 3, M. Krawczyk 3, R.Sachser 4, M. Huth 4, K.Yu. Guslienko 5,6, G.N. Kakazei 2, O.V. Dobrovolskiy 1,4 1 Department of Physics, V. N. Karazin Kharkiv National University, Kharkiv, Ukraine 2 IFIMUP-IN/Department of Physics and Astronomy, University of Porto, Porto, Portugal 3 Faculty of Physics, Adam Mickiewicz University, Poznan, Poland 4 Physikalisches Institut, Goethe University, Frankfurt am Main, Germany 5 Departamento Física de Materiales, Universidad del País Vasco UPV/EHU, San Sebastián, Spain 6 IKERBASQUE, the Basque Foundation for Science, Bilbao, Spain OPTICS, PHOTONICS AND OPTICAL SPECTROSCOPY P25 P26 P27 MAGNETIC FIELD INDUCED PHASE TRANSITION AND THE LOW FREQUENCY DYNAMIC IN KDy(MoO 4 ) 2 K.V. Kutko 1, S.N. Poperezhai 1, N.M. Nesterenko 1, D.L. Kamenskii 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 High Field Magnet Laboratory (HFML EMFL), Radboud University, Nijmegen, The Netherlands FEATURES OF THE EXCITON DYNAMICS AND SELF-TRAPPING OF CARBOCYANINE J-AGGREGATES FORMED IN POLYMER FILMS А.V. Sorokin 1, I.Yu. Ropakova 1, S. Wolter 2, R. Lange 2, I. Barke 2, S. Speller 2, S.L. Yefimova 1, Y.V. Malyukin 1, S. Lochbrunner 2 1 Institute for Scintillation Materials NASU, SSI Institute for Single Crystals NASU, Kharkiv, Ukraine 2 Institute of Physics and Department of Life, Light and Matter, University of Rostock, Germany FEATURES OF LOW TEMPERATURE LUMINESCENCE OF FULLERITE NITRIDE C 60 N X P.V. Zinoviev, V.N. Zoryansky, V.V. Meleshko B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine

26

27 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 25 INTERNATIONAL ASSOCIATION OF PHYSICS STUDENTS The organizing committee of the 10th International Conference for Professionals and Young Scientists Low Temperature Physics 2019 is pleased to express the great gratitude to the International Association of Physics Students (IAPS) for the sponsorship of this event and the fruitful interaction for the benefit of physics students the participants and guests of the conference, and glad to present here the main information about IAPS. IAPS is an association of physics students and student societies from around the globe, working to promote peaceful collaborations amongst them. IAPS members are represented by National and Local committees, who meet regularly to ensure the relevance of our activities. IAPS also includes Individual members, in locations where no national or local committees exist. IAPS counts on its members to collaborate and co-ordinate national and international projects related to Physics. IAPS current member societies comprises of 18 National Committees including 2 provisional ones, 29 Local Committees including 3 provisional ones, and around 150 Individual Members all over the world. Since 1987, IAPS has worked continuously to support friendly relations and collaboration between physics students. IAPS supports their members in their academic and professional work, as well as discussing and acting on scientific, social and cultural issues. IAPS is a recognised nongovernmental organisation run entirely by students from around the world with a spirit of mutual understanding and equality. IAPS organizes an annual International Conference for Physics Students (ICPS); an annual physics competition, Physics League Across Numerous Countries for Kick-ass Students (PLANCKS); the visits to global research institutions, summer schools, exchange programmes, outreach activities, and multinational meetings all over the world. If you are interested to know more anout IAPS, please visit the web-site or contact to IAPS Executive Committee through members@iaps.info. ESTABLISHMENT AND DEVELOPMENT OF IAPS In 1985, a group of Hungarian physics students decided to organize a meeting with their peers from all over the world. After a great deal of work, student physicists came together for their first conference, the International Conference for Physics Students, in Budapest, Hungary in The great success of the first conference led to another being held the next year in Debrecen, Hungary. During this conference, participants expressed their desire to form an international body to encourage peaceful cooperation and mutual understanding between physics students. The International Association of Physics Students was born on 12th September 1987 when the first Charter was signed. This established IAPS as a multinational, non-profit, non-governmental organisation run entirely by students from across the globe. To ensure that future IAPS members would be able to learn about cutting-edge developments in physics and in other scientific fields, interact with professional physicists to learn about careers and opportunities in physics and to enjoy the benefits of interacting with their peers from other cultures, the founders of IAPS also agreed that the International Conference for Physics Students should occur annually. Hence since then, the ICPS has been organised in a different country every year, creating an annual forum of about 350 physics students. In 1993 the first conference outside Europe was organised in Bodrum, Turkey (Asia). In 1996, the Journal of International Association of Physics Students (jiaps) became a formal printed publication of the organisation. The jiaps is published once a year and distributed

28 26 Sponsors and co-organizers for free during ICPS. It contains scientific articles, IAPS event reports and any news of interest to IAPS members. Any physics student who would like to publish an article on jiaps may send it to the editors In 2002, IAPS expanded its activities to include a summer school with the first held in Coimbra, Portugal with a Computational Physics theme. Through its existence, IAPS has been accumulating a number of affiliations with several international organisations. These include the European Physical Society (EPS), the Institute of Physics (IOP), and the International Union of Physics and Applied Physics (IUPAP). Thus, in 2002, ICPS was organized for the very first time as a joint conference with the European Physical Society in Budapest, Hungary. IAPS is run by students from all over the world. The IAPS overseeing governing body known as the General Meeting (General Assembly) is comprised of elected officers from the National and Local committee members. All members may access documents related to a General Assembly of IAPS. A permanent office is maintained in Mulhouse, France with the European Physical Society. Apart from the elected officers, IAPS welcomes all students and other people who are willing to volunteer their time, to champion the course of IAPS in becoming a concrete and formidable organisation that will address the concerns and needs of young physicists across the world. IAPS EVENTS AND ACTIVITIES IAPS major annual event, the International Conference for Physics Students, is organised each year in a different member country. It allows physics students to present their work to an international audience and establish contacts among their peers from around the world. IAPS is also organising yearly its own Physics Competition, the Physics League Across Numerous Countries for Kickass Students (PLANCKS). IAPS s activities focus is wide and includes activities with an international reach that IAPS sets up or co-coordinates or in which it participates and those that are initiatives of IAPS members, with local or national range, some of which, like PLANCKS, become IAPS-organized events. If the event is open to all IAPS members, it is defined as an IAPS event. IAPS s own and co-coordinated activities, along with those in which it participates, serve the purpose of focusing all IAPS members on particular, widely shared objectives: coordinating efforts on outreach with School Day, by choosing a theme each year on which all participating IAPS members concentrate to promote a specific area of Physics; providing opportunities to travel to and get to know theoretical or experimental research facilities and universities with excursions like #iaps2cern, #iaps4fusion and PAPAP; contributing to global UNESCO goals for the sharing of educational, cultural and scientific heritage through participation in the International Day of Light; fostering a social and professional environment of cooperation, collaboration and friendship between IAPS s members by organising PLANCKS and ICPS. Expanding on events in which it is directly involved, IAPS always welcomes member committees or other groups of IAPS members to organize events with a specific local, national or transnational motivation, supporting these financially or logistically, most importantly through grants. These are available for excursions, outreach events, exchange projects, cooperation between IAPS local or national committees and collaboration with organizations affiliated to other international student s associations, but creativity is encouraged towards planning something entirely different that can fulfill, just as well, our objectives. If you are interested in organising an event or an excursion, get in contact with the IAPS through ec@iaps.info. If you are interested to participate in IAPS events, the caledar of the upcoming events is available on the link

29 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine PLENARY LECTURES OF INVITED SPEAKERS Plenary Lectures of Invited Speakers 27

30

31 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine BORIS VERKIN, PHYSICIST AND FOUNDER OF THE INSTITUTE FOR LOW TEMPERATURE PHYSICS AND ENGINEERING G.E. Grechnev B.Verkin Institute for Low Temperature Physics and Engineering of the NASU, Kharkiv, Ukraine Boris Verkin was a brilliant experimental physicist and teacher, but, above all, he was an outstanding organizer of science. This rare gift, which included a deep understanding of physics, intuition, foresight, purposefulness, he has dedicated to creating a unique structure the Institute for Low Temperature Physics and Engineering. At that time, 1960, hardly anyone adequately imagined which circle of unknown quantum phenomena and which application possibilities in the new technique and in everyday life are hidden in the region of low and ultralow temperatures. The institute is not only a large building built for scientific research. There are also people and their affairs. Boris Verkin knew how to find, attract with his enthusiasm and personal charm, infect with scientific problems talented physicists whom he employed and involved in research activity in the Institute. He took care of and supported them. Verkin was able to create at the Institute a community of physicists, mathematicians and designers, and to ensure the realization of fruitful ideas in specific products. Boris Verkin was encyclopedically formed and enriched the range of promising areas of research in the main areas of low-temperature condensed matter physics: in electronic properties of metals, superconductivity, magnetism, quantum electronics, properties of cryocrystals, quantum crystals and quantum liquids, structure and mechanical properties of materials, molecular biophysics, physics and technology at ultralow temperatures. The scientific directions chosen by him have been fruitfully developed at the institute to this day. Boris Verkin initiated and developed a wide range of applications of low temperatures in instruments engineering, electrical engineering, space technology, medicine, biology, and the food industry. Therefore the interests of the institute and its activity stretched from the terrestrial and sea depths to the neighboring planets. 29

32 30 Invited Speakers GRAPHENE AND 2D MATERIALS FOR NEXT GENERATION PHOTONICS, OPTO-ELECTRONICS AND ELECTRONICS A. Baldycheva Centre for Graphene Science & Nano Engineering Science and Technology Group, College of Engineering, Mathematics and Physical Sciences, University of Exeter, UK Graphene is an emerging material for photonics, optoelectronics and electronics due to unique physical properties such as high electrical conductivity, optical transparency and mechanical flexibility. These properties can be further enhanced or tailored to fit specific device functionalities by means of chemical functionalization. A recent example of the potential of chemical functionalization is the intercalation of few-layer-graphene with FeCl3 (dubbed GraphExeter), which is currently the best performing carbon-based transparent conductor, with resilience to extreme conditions and potential for transparent photo-detectors, flexible photovoltaic and organic light emitting devices and foldable light-emitting devices. Among other emerging optoelectronic materials, fluid-dispersed atomically thin 2D nanocomposite materials demonstrate great promise for the next generation of multi-functional optoelectronic systems with a wide range of important applications, such as renewable energy, optical communications, bio-chemical sensing, and security and defence technologies. In this talk I will review our latest developments in the use of graphene and functionalized graphene for electronics, photonics and optoelectronics. I will present our recent studies on the use of high quality graphene for next generation light emitting devices and for flexible, wearable touchsensors. I will review our recent demonstration of 2D heterostructures for video-frame-rate imaging applications, intelligent design of 2D devices and GraphExeter photodetectors for high-definition sensing and video technologies. I will also present our most recent results on dynamically controlled three-dimensional self-assembly of suspended 2D liquid exfoliated nano-flakes, which provides a breakthrough route for technological realization of 2D material based 3D metaarchitectures.

33 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine LASER DRIVEN ION ACCELERATION FROM A CRYOGENIC HYDROGEN RIBBON 31 T.V. Chagovets Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Prague, Czech Republic timofej.chagovets@eli-beams.eu Laser driven ion acceleration is a widely investigated research topic in the field of physics nowadays as a result of the recent fast development of high power laser systems allowing to explore laser-matter interaction at ultrahigh laser intensities ( W/cm 2 ). Among different physical mechanisms of laser-driven ion acceleration that have been investigated to date, Target Normal Sheath Acceleration (TNSA) is the most robust and experimentally investigated one. In this regime ions are accelerated at the rear side of a thin (micrometer) target in a quasi-electrostatic sheath formed by fast electrons propagating from the target front side. The acceleration process takes place till restore of charge neutrality and finally both ions and electrons move together in a ballistic way. The ion energy distribution depends on both laser power and target nature. Laser accelerated ion beams draw attention for their potential multidisciplinary applications, e.g. inertial confinement fusion, probing of ultrafast field dynamics or, ultimately, laser-based radio oncology (namely hadrontherapy). Multidisciplinary applications, especially medical ones, have stringent requirements for laser-accelerated ions, such as high-energy ( MeV), high average current (in principle achievable by using 1 10-Hz lasers), target purity, repeatable generation, and monochromaticity. The recently built new research infrastructure ELI Beamlines, which is a part of the Extreme Light Infrastructure (ELI) project, is intended to provide high repetition rate PW-class laser beam for basic and applied research. Besides lasers, it is equally important to develop novel target media specifically tailored to advanced interaction regime. Traditional targets like metals or carbon foils usually have some limitations which make laser-accelerated beams not suitable for applications. Thin cryogenic targets (1 50 μm) of high purity with relatively low electron density ( cm 3 ), capable of producing only protons (with no contaminants) and of operating at a high repetition rate as both refreshable and debris free are very promising. From this perspective, both liquid and solid cryogenic targets are currently being considered and several approaches are being explored and developed. The ELISE cryogenic target delivery system designed and developed at the Low Temperature Laboratory of CEA enables the production of the continuous flow of a solid-h 2 slab (ribbon) through a newly designed extrusion apparatus that does not contain any movable parts [2]. A research group from SLAC National Accelerator Laboratory, USA has designed a cryogenic microjet source, which can deliver a continuous stream of liquid hydrogen with a diameter of a few microns that is compatible with high-intensity and/or high-repetition-rate laser-plasma experiments [3]. Using a cryogenic target both liquid and solid, it was demonstrated that a multi-mev pure proton beam can be produced through high-intensity laser interaction [3]. The high purity, limited size, moderate density, and ability to use hydrogen isotopes make this target highly favorable for innovative studies. The generation of pure hydrogen plasma has advantages from the experimental point of view in terms of plasma modelling and characterization (single ion species), as well as for future multidisciplinary applications of laser-accelerated proton beams in cancer therapy. [1] A. Macchi, M. Borghesi, and M. Passoni, Rev. Mod. Phys. 85, 751 (2013). [2] S. Garcia, D. Chatain, and J. P. Perin, Laser Part. Beams 32, 569 (2014). [3] J. B. Kim, S. Göde, and S. H. Glenzer, Review of Scientific Instruments 87, 11E328 (2016). [4] D. Margarone et al., Physical Review X 41030, 6 (2016).

34 32 Invited Speakers PROBLEMS OF METHANE EXPLOSION AND BLAST ENERGY SUPPRESSION IN COAL MINES M. Chikhradze 1,2, E. Mataradze 1, K. Tavlalashvili 1, G. Janikashvili 1 1 G.Tsulukidze Mining Institute,7 E.Mindeli str., Tbilisi 0186, Georgia 2 Georgian Technical University, 77 Kostava str., Tbilisi 0160, Georgia m.chikhradze@gtu.ge The accidents in coal mines from methane/coal dust explosion still remains as the problem in many countries. In spite of the strict safety regulations frequently the negative consequences can not be avoided. Methane explosion is considered as one of the most dangerous to the miners and infrastructure [1]. Considering the growing threat of methane explosion, the development of fast - acting energy suppression systems seems to be urgent to increase the safety level of an underground coal mine. The designing and development of effective explosion energy suppression system will significantly decrease the damage of infrastructure and fatal outcomes in coal mines. This paper focuses on technical solutions to be used in designing a protective system for minimizing the consequences of methane explosions in coal mines. Based on the analyses of recent studies [2,3] were designed and created prototype of new protective system including explosion detector block, activation block with wireless device and shock wave energy absorber. As a suppression device an absorber with a pyrotechnic element were used, which ensures the discharge of dispersed water. Finally presented the results of experiments carried out for the determination of blast suppression effect. Experimental investigations have been carried out at G. Tsulukidze Mining Institute. This work was supported by Shota Rustaveli National Science Foundation of Georgia (SRNSFG) [Grant #FR17_471, Project Title: Investigation of Explosion Suppression and Development of Design Parameters of Protective System ]. [1] Long Shi, Jinhui Wang, Guomin Zhang, Xudong Cheng,Xianbo Zhao, A risk assessment method to quantitatively investigate the methane explosion in underground coal mine, Process Safety and Environment Protection (107), pp , [2] I. Lomidze, N. Chikhradze, E. Mataradze, T. Krauthammer. A Shock Wave Absorber: The Device and Mathematical Model. Proceedings of the 10th International Multidisciplinary Scientific Geoconference, pp , [3] E. Mataradze, T. Krauthammer, N. Chikhladze, E. Chagelishvili. Influence of Liquid Phase Concentration on Shock Wave Attenuation in Tunnels. Proceedings of the 21th International Symposium on Military Aspects of Blast and Shock, Jerusalem, Israel, 2010.

35 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine UNCONVENTIONAL MAGNONICS: FROM NANO-OPTICS TO SUPERCONDUCTIVITY 33 O.V. Dobrovolskiy Physikalisches Institut Goethe University, Frankfurt am Main, Germany In the recent years, magnonics (the study of spin waves precessional excitations of ordered spins in magnetic materials) has emerged as one of the most rapidly growing research fields in magnetism [1,2]. This is largely because of the recent advances in the understanding of fundamental properties of spin waves in magnetic micro- and nanostructures, rendering magnonics as a potential rival of or complement to semiconductor technology for data communication and processing [3]. At the same time, loss reduction, shortening of the wavelength of spin waves [4], and the associated miniaturization of the implemented magnonic concepts and devices remain major challenges in both experimental research and technological development in magnonics. This is why the development of new approaches and the implementation of ideas originating from other domains of physics is currently at the forefront of the magnonics research. In my talk, I will primarily address two groups of concepts in magnonics associated with nano-optics and superconductivity. In spin-wave nano-optics, I will dwell on novel approaches to generate and manipulate spinwave beams [5,6] in graded-index magnetic media fabricated by focused electron beam-induced deposition (FEBID) [7]. A particular attention will be paid to spin-wave lenses based on the spinwave phase-tuning using a single nanodefect [8]. At the interface of magnonics and fluxonics research (fluxonics is the study of properties and dynamics of vortices in superconductors [9]), an important conceptual similarity will be exploited: Disturbances in magnetic ordering in magnetic materials propagate in the form of spin waves (magnons) while magnetic fields penetrate superconductors as a lattice of magnetic flux quanta (fluxons). Recently, the interaction of spin waves with a flux lattice in ferromagnet/superconductor Py/Nb bilayers has been evidenced [10]. In particular, it has been demonstrated that, in this system, the magnon frequency spectrum exhibits a Bloch-like band structure with forbidden-frequency gaps which can be tuned by the biasing magnetic field. Furthermore, Doppler shifts have been observed in the frequency spectra of spin waves scattered on a flux lattice moving under the action of a transport current in the superconductor, thereby setting the stage for magnon-fluxonics as a new research domain at the interface between superconductivity and magnetism. Research leading to this results has received funding from the DFG in the framework of the Collaborative Research Center SFB/TRR-173 Spin+X (Project B04) and Grant (DO1511/3-1). Furthermore, support from the European Commission within the framework of the MSCA-RISE program under Grant Agreement No (MagIC) and COST Action CA16218 (NANOCOHYBRI) of the European Cooperation in Science and Technology is acknowledged. [1] V. V. Kruglyak, S. O. Demokritov, and D. Grundler, J. Phys. D: Appl. Phys. 43, (2010). [2] M. Krawczyk and D. Grundler, J. Phys.: Condens. Matter 26, (2014). [3] A.V. Chumak, V Vasyuchka, A. Serga, B. Hillebrands, Nat. Phys. 11, 453 (2015). [4] D. Grundler, Nat. Nanotechnol. 11, 407 (2016). [5] P. Gruszecki et al. Sci. Rep. 6, (2016). [6] Körner, J. Stigloher, and C. H. Back, Phys. Rev. B 96, (2017). [7] M. Huth, F. Porrati, O. V. Dobrovolskiy, Microelectron. Engineering 185, 9 (2018). [8] O.V. Dobrovolskiy et al. ACS Appl. Mater. Interf. DOI: /acsami.9b02717, (2019). [9] O. V. Dobrovolskiy, Physica C 533, 80 (2017). [10] O. V. Dobrovolskiy et al. Nat. Phys. 15, 477 (2019), arxiv:

36 34 Invited Speakers ELECTRON-PHONON COOLING POWER IN ANDERSON INSULATORS M.V. Feigel'man 1, V.E. Kravtsov 2,1 1 L.D.Landau Institute for Theoretical Physics., Chernogolovka, Moscow region, Russia 2 International Center for Theoretical Physics, Trieste, Italy feigel@landau.ac.ru A theory for electron-phonon energy exchange in Anderson insulators with long localization length is developed. The major contribution to the cooling power as a function of electron temperature is shown to be directly related to the correlation function of the local density of electron states, which is enhanced near the localization transition by multi-fractality and by the presence of Mott's resonant pairs of states. The theory we develop explains huge enhancement of the cooling power observed in insulating Indium Oxide films as compared to predictions of standard theory for disordered metals.

37 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine CATIONIC SUBSTITUTION vs. MULTIFERROICS PROPERTIES IN METASTABLE PEROVSKITES 35 E. Gilioli 1, D. Delmonte 1, A. Gauzzi 2, F. Mezzadri 1, M. Verseils 3 1 CNR-IMEM, Institute of Materials for Electronic and Magnetism, Area delle Scienze 37/A, 43124, Parma, Italy 2 IMPMC, Sorbonne Université-CNRS-IRD-MNHN, 4, place Jussieu, Paris, France 3 Synchrotron SOLEIL, L Orme des Merisiers, Saint-Aubin, France edmondo.gilioli@cnr.it Multiferroic materials, beside the fascinating fundamental research, are gaining increasingly interest for their potential applications in many fields, whenever the electrical/magnetic properties can be mutually controlled. Unfortunately, these compounds are extremely rare in nature and the coupling (between magnetism and ferroelectricity in the most wanted case) is still too weak for practical use. The synthesis under high pressure/high temperature (HP/HT) is a powerful tool in the search for new multiferroics and the perovskite structure is a model system, for its ability to accommodate the pressure-induced distortions in different ways [1]. A selection of bulk manganites with perovskite-based compounds synthesized by HP/HT techniques at IMEM-CNR will be presented. In particular, the surprising role of the cationic substitution in the quadruple perovskite AMn 7 O 12 (A= Na, Ca, Bi, La, Y) in inducing and affecting the magneto-electric coupling, will be discussed. [1] E. Gilioli and L. Ehm, IUCrJ 1 (6), (2014).

38 36 Invited Speakers PHASE TRANSITIONS IN NEW 2D FRUSTRATED MAGNETS Cu 3 R(SeO 3 ) 2 O 2 Cl STUDIED BY OPTICAL SPECTROSCOPY S.A. Klimin Institute of Spectroscopy, Russian Academy of Sciences, 5, Fizicheskaya Str., Troitsk, Moscow, , Russia klimin@isan.troitsk.ru Cu 3 RE(SeO 3 ) 2 O 2 Cl is a new family of magnetic compounds in which an interplay between two magnetic subsystems exists, namely, between rare-earth (RE) and copper ones. Parent compound, natural mineral francisite Cu 3 Bi(SeO 3 ) 2 O 2 Cl, has one magnetic ion, Cu 2+ and orders antiferromagnetically at T N =24 K. In the crystal, copper atoms compose two-dimensional (2D) layers with a buckled Kagome lattice. Due to that, francisites attract interest of the magnetic community as a 2D frustrated magnet [1,2]. Up to now a series of Cu 3 RE(SeO 3 ) 2 O 2 Cl compounds were synthesized with replacement of bismuth by a rare earth (RE) element, while the crystallographic structure remains the same [3]. Introduction of a RE magnetic subsystem influences the magnetism of copper subsystem and leads to various scenarios of magnetic behavior. In this paper the results of studying of magnetic properties of RE francisites by means of a temperature-dependent high-resolution spectroscopy are presented. Magnetic ordering was registered either by splitting of Kramers doublets or by repulsion of CF levels of f-ions in a staggered magnetic field. The splittings demonstrate anisotropic behaviour: Δ k = (g ki B eff,i ) 2, where g ki, B eff,i are i-th (i = x, y, z) components of g-factor and effective magnetic field acting on k-th doublet, respectively. Experimental optical data enabled to calculate the contribution of the RE ions Fig.1 SR transition in (a,b) Y and (c,d) Sm fracisites. into the thermodynamic characteristics. The most interesting effect of the d- and f- magnetic subsystems interplay is spin-reorientation (SR) transitions found in the cases with RE = Sm and Yb [4,5]. The SR transitions take place due to the single-ion anisotropy of RE ion when it does not coincide with the anisotropy of copper magnetic subsystem and is strong enough to reorient copper moments. However, different scenarios for SR transition are realized in samarium and ytterbium compounds, namely, the second order and the first one, respectively (Fig. 1). The reason for that could lie in the different types of single-ion anisotropies of samarium and ytterbium. The situation in francisites could be the same as in another family of RE compounds (R 2 BaNiO 5 ) with similar symmetry properties of the RE cite, where different types of single-ion anisotropies for different rare earths are realized. Depending on anisotropic interactions in a crystal, in one case the spin-reorientation transition can be realized as spin-flop-like (first order) or as gradual rotation (second order). The support of RFBR (grant ) is acknowledged. [1] M. Pregelj, O. Zaharko, A. Günther et al., Phys. Rev. B, Vol. 86, (2012). [2] K.V. Zakharov, E.A. Zvereva, P.S. Berdonosov et al., Phys. Rev. B, Vol. 90, (2014). [3] P.S. Berdonosov, V.A. Dolgikh, Rus. J. Inorg. Chem., Vol. 53, 1353 (2008). [4] K.V. Zakharov, E.A. Zvereva, M.M. Markina, et al., Phys. Rev. B, Vol. 94, pp (2016). [5] M.M. Markina, K.V. Zakharov, E.A. Ovchenkov., et al., Phys. Rev. B, 96, (2017).

39 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine HYDROGEN STORAGE IN METALLIC MATERIALS ON BASIS OF MAGNESIUM 37 L. Kral 1, J. Cermak 1,2 1 Institute of Physics of Material, AS CR, v.v.i., Zizkova 22, Brno, Czech Republic 2 CEITEC-Institute of Physics of Materials, AS CR, Zizkova 22, CZ Brno, Czech Republic lkral@ipm.cz Hydrogen is a very prospective and eco-friendly fuel which can bring economic and environmental benefits. However, operation with hydrogen is hazardous due to its extremely high flammability. Nevertheless, the advantages of hydrogen economy remain a permanent challenge and hence, new ways are sought that could lower hazards as much as possible. One of technology issues that impede expected future hydrogen economy is the lack of safe, efficient and economic hydrogen storage (HS). At present, there are two main ways how to store hydrogen: compression of gaseous hydrogen and liquefaction. None of these storage techniques is sufficiently efficient and free of hazards especially for mobile applications. It appeared that hydrogen can be stored in solids, where surprisingly high gravimetric and volumetric density can be reached. Many HS materials were investigated that store hydrogen either by physisorption or by chemisorption. Unfortunately up to now, none of them showed sorption characteristics that would fulfil all demands of technical practice. Our group is involved in research of perspective chemisorbants mainly based on Mg. Magnesium is one of prospective storage material because of their high theoretical hydrogen storage capacity (7.6 wt.%), volumetric capacity (110 g L -1 ), the highest energy density of all reversible hydrides (9 MJ kg 1 ), Earth abundance and low cost. However, pure magnesium has poor sorption properties. In recent years, the kinetics of sorption properties of magnesium-based materials has been significantly improved. In respect of too high thermodynamic stability of Mg hydrides, which hinder the operation at low temperatures, only moderate success was reported in the literature. Very interesting results were achieved with materials prepared by reactive milling and doped by effective catalysts. However, the kinetics of hydrogen desorption under about 250 C remains an open issue.

40 38 Invited Speakers TAILORING CUSTOM POLARIZATION STATES C. López-Mariscal Department of Physics and Astronomy, Appalachian State University, Boone, NC, USA Underwater Photonics, Cozumel, Mexico We have developed a technique to straightforwardly generate arbitrary vector beams, with tailored polarization states. We take advantage of the ability of spatial light modulators to simultaneously generate two components of an electromagnetic field by and subsequently recombining them in one complex state. Our experimental results show the versatility and robustness of this technique for the generation of vector beams with arbitrary states of polarization. Our work represents a step towards reliable underwater optical communications. [1] B. Perez-Garcia, C. López-Mariscal, R. Hernandez-Aranda, and J. Gutiérrez-Vega, "On-demand tailored vector beams," Appl. Opt. 56, (2017).

41 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine QUANTUM ANALOGUE OF ENERGY EQUIPARTITION THEOREM 39 P. Bialas, J. Spiechowicz, J. Łuczka Institute of Physics and Silesian Center for Education and Interdisciplinary Research, University of Silesia, Chorzów, Poland One of the fundamental law of classical statistical physics is the equipartition energy theorem which states that for each degree of freedom the average kinetic energy is equal to E = kt /2, where k is the Boltzmann constant and T is temperature of the system. For quantum systems it does not hold. We prove that for a free quantum Brownian particle coupled to thermostat consisting of harmonic oscillators of temperature T, the mean kinetic energy of the Brownian particle is equal to mean kinetic energy per one degree of freedom of the thermostat free oscillators. The averaging is twofold: (i) over the Gibbs canonical state for free oscillators of the thermostat and (ii) over frequencies of those thermostat oscillators which contribute to the Brownian particle energy according to the probability distribution, which is a cosine Fourier transform of the response function which, in turn, solves the quantum generalized Langevin equation for the Brownian particle. We show that this relation can be obtained from the fluctuation-dissipation theorem derived within the linear response theory and is universal in the sense that it holds true for any linear and non-linear systems in contact with bosonic thermostat. [1] J. Spiechowicz, P. Bialas and J. Łuczka, Quantum partition of energy for a free Brownian particle: Impact of dissipation, Phys. Rev. A 98, (2018). [2] P. Bialas, J. Spiechowicz, J. Łuczka, Partition of energy for a dissipative quantum oscillator, Sci. Rep. 8, (2018). [3] P. Bialas, J. Spiechowicz and J. Łuczka, Quantum analogue of energy equipartition theorem, J. Phys. A 52 (2019).

42 40 Invited Speakers APPLICATION OF OPTICAL ANGULAR MOMENTUM AND QUANTUM ENTANGLEMENTS IN BIOMEDICAL TISSUE DIAGNOSTICS I. Meglinski Laboratory of Opto-Electronics and Measurement Techniques, University of Oulu, Oulu, Finland In turbid tissue-like scattering medium the conventional polarized light, scattered multiple number of times, is depolarized, and the depolarization rate depends strongly on the size and shape of scattering particles, as well as on the number of scattering events. In fact, the structure of light can be more complicated when the polarization of light across the laser beam can be radially or azimuthally polarized and carry orbital angular momentum. When these so-called structured light beams, such as cylindrical vector beam (CVB) and/or Laguerre-Gaussian (LG) beams, propagates through a turbid tissue-like scattering medium, either anisotropic or inhomogeneous, the spin or angular momentum are changed that leads to spin-orbit interaction. The spin-orbit interaction leads to the mutual influence of the polarization and the trajectory of the light propagation. We investigate the applicability of using CVB and LG beams for optical diagnostics of biological tissues. In current presentation propagation of CVB and LG beams in anisotropic turbid tissue-like scattering media is considered in comparison to conventional transfer of Gaussian beams. We demonstrate that by applying CVB and LG beams the sensitivity is increased at least twice in comparison to the conventional tissue polarimetry approach. Both experimental and theoretical results suggest that there is a high potential in application of structured light in tissue diagnosis. Finally, the perspectives of using quantum entanglements for diagnostic purpose are discussing.

43 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine OPTICAL SPECTROSCOPY OF EXCITONS WITH SPATIALLY SEPARATED ELECTRONS AND HOLES IN NANOHETEROSTRUCTURES WITH SEMICONDUCTOR AND DIELECTRIC QUANTUM DOTS S.I. Pokutnyi Chuiko Institute of Surface Chemistry of NAS of Ukraine, 17 General Naumov Str., Kyiv, 03164, Ukraine In [1, 2] study, we find that the binding energy of an exciton formed from an electron and a hole spatially separated from each other (the hole is moving within a quantum dot (QD), and the electron is localized above the spherical QD matrix interface) in a nanosystem containing semiconductor (germanium) and insulating aluminium oxide QDs is substantially increased (by nearly two orders of magnitude) compared to the exciton binding energy in an silicon and aluminium oxide single crystal. It is established that, in the band gap of an germanium and aluminium oxide QDs, there is a band of exciton states (formed from a spatially separated electron and hole). It is shown that there exists the possibility of experimentally detecting the ground and excited exciton states in the band gap of an germanium and aluminium oxide QDs at room temperature from the absorption and transmittance spectra of the nanosystem. The effect of a substantial increase in the exciton binding energy offers considerable scope for the use of insulating nanoheterostructures as the active region of nanolasers operating at excitonic transitions [1, 2]. The theory of excitons from spatially separated electrons and holes (the hole moves in volume QD, and the electron is localized over the spherical surface boundary of (QD/matrix)), developed in [3, 4], for the case in which centrifugal energy of the electron is considered in the potential energy of the exciton. It has been shown that the taking into consideration centrifugal energy in the potential energy of the exciton leads to the occurrence of the quasi-stationary states in the band of the surface exciton states, which with the increase of QD radius transfers into stationary state. It is established that the light spectrum of the interband absorption (emission) of nanosystems consisting of the energy bands which are formed by the electron between quasi-stationary and stationary states, and intraband absorption spectra from the bands caused by electron transitions between stationary states [3, 4]. [1] S.I. Pokutnyi, Low Temp. Phys. 42, 1151 (2016) [Fiz. Nizk. Temp.42, 1384 (2016)]. [2] S.I. Pokutnyi, Semiconductors. 49, 1311 (2015). [3] S.I. Pokutnyi, Low Temp. Phys. 44, 819 (2018) [Fiz. Nizk. Temp. 44, 1045 (2018)]. [4] S.I. Pokutnyi, J. Nanophoton. 12, (2018). 41

44 42 Invited Speakers QUANTUM INFORMATION PROCESING WITH MICROWAVE PHOTONIC STATES IN SUPERCONDUCTING JOSEPHSON CIRCUITS V.S. Shumeiko Dept. Microtechnology and Nanoscience, Chalmers University of Technology, Kemivägen 9, Göteborg, 41296, Sweden Josephson effect is widely used in microwave electronics for building nonlinear and lossless circuit elements. However, the unique combination the nonlinearity and absence of dissipation becomes truly significant in the quantum regime. Here the Josephson circuits function as controllable artificial atoms, which makes them indispensable building blocks for quantum information processing. In this talk I review recent progress in research on quantum parametric phenomena in superconducting electrical circuits. This research is part of emerging and rapidly growing quantum information technology based on superconducting Josephson junctions - circuit quantum electrodynamics (c-qed). Recent attention to parametric effects in c-qed was motivated by practical needs for ultrasensitive quantum limited amplifiers for detection of extremely weak, of single-photon intensity microwave signals that carry information about superconducting qubits. Exploration of c-qed parametric devices reveals a wide range of remarkable quantum effects, such as dynamical Casimir effect, ultrastrong light-matter interaction, vacuum squeezing, photonic quantum cat states. I will discuss recent experiments on parametric amplification and frequency conversion, selfsustained parametric oscillations and oscillations with period multiplying. I will also outline a novel approach to quantum information processing within c-qed, which is based on encoding quantum information in parametrically generated photonic cat states.

45 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine LOGARITHMIC FLUIDS 43 K.G. Zloshchastiev Institute of Systems Science, Durban University of Technology, Durban 4000, South Africa A living review of past, current and future studies of the so-called logarithmic fluids is presented. We begin by considering a large class of condensate-like strongly-interacting materials and many-body systems, which allow description in terms of a single macroscopic function, at least effectively or in a leading-order approximation. Recently proposed statistical mechanics arguments [1] and previously known Madelung hydrodynamical presentation [2] reveal that the logarithmic nonlinearity occurs in equations describing such matter. From the viewpoint of classical fluid mechanics, the resulting equations describe in the simplest case the irrotational and isothermal flow of a two-phase barotropic compressible inviscid fluid with internal capillarity and surface tension [3]. We demonstrate the emergence of Hilbert space and spontaneous symmetry breaking in this class of fluids, which leads to a number of wave-mechanical and topological effects [4]. The applications of such fluids can be found in both classical and quantum physics. In a classical case, one can show that the logarithmic fluids can be used for describing various Korteweg-type materials, such as magmas in volcanic conduits [3,4], whose studies have a long history [5]. In quantum physics, such fluids can be used for describing strongly-interacting quantum fluids [6-8], including He II, a superfluid component of He-4 [9]. We show the relationship between the logarithmic fluids and those described by polynomially nonlinear wave equations, such as the Gross-Pitaevskii one, which can be regarded as perturbative or low-density limits of the former [1]. Yet another range of applications of the logarithmic matter can be found in a theory of physical vacuum. Using the logarithmic model and machinery of condensed matter, one can formulate an essentially quantum post-relativistic theory which recovers special and general relativity in the phononic (low-momenta) limit, but otherwise has rather different tenets, foundations and predictions. We show that the paradigm of fundamental background superfluid opens up an entirely new prospective on the emergence of the Lorentz symmetry and spacetime notions, spontaneous symmetry breaking and mass generation mechanisms, finite-size elementary particles and Q-balls, dark matter/energy candidates, black holes, cosmological singularities, transluminal phenomena, and so on [10-15]. [1] K.G. Zloshchastiev, Z. Naturforsch. A 73, 619 (2018). [2] Y.A. Rylov, J. Math. Phys. 40, 256 (1999). [3] S. De Martino, M. Falanga, C. Godano and G. Lauro, Europhys. Lett. 63, 472 (2003). [4] K.G. Zloshchastiev, Europhys. Lett. 122, (2018). [5] J.E. Dunn and J. Serrin, Arch. Rat. Mech. Anal. 88, 95 (1985). [6] A. Avdeenkov and K.G. Zloshchastiev, J. Phys. B: At. Mol. Opt. Phys. 44, (2011). [7] B. Bouharia, Mod. Phys. Lett. B 29, (2015). [8] K.G. Zloshchastiev, Z. Naturforsch. A 72, 677 (2017). [9] K.G. Zloshchastiev, Eur. Phys. J. B 85, 273 (2012). [10] K.G. Zloshchastiev, Grav. Cosmol. 16, 288 (2010). [11] K.G. Zloshchastiev, Acta Phys. Polon. B 42, 261 (2011). [12] K.G. Zloshchastiev, Phys. Lett. A 375, 2305 (2011). [13] V. Dzhunushaliev and K.G. Zloshchastiev, Cent. Eur. J. Phys. 11, 325 (2013). [14] T. C. Scott, X. Zhang, R. B. Mann, and G. J. Fee, Phys. Rev. D 93, (2016). [15] V. Dzhunushaliev, A. Makhmudov, and K.G. Zloshchastiev, Phys. Rev. D 94, (2016).

46

47 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 45 Electronic ELECTRONIC PROPERTIES OF CONDUCTING Properties of AND SUPERCONDUCTING SYSTEMS Conducting and Superconducting Systems

48

49 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine FEATURES OF THE EXCESS CONDUCTIVITY BEHAVIOR IN A MAGNETIC SUPERCONDUCTOR Dy 0.6 Y 0.4 Rh 3.85 Ru 0.15 B 4 47 A.L. Solovjov 1, A.V. Terekhov 1, E.V. Petrenko 1, L.V. Omelchenko 1 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine pertrenko@ilt.kharkov.ua The temperature dependences of the excess conductivity σ (T) and the possible pseudogap state Δ*(T) in the Dy 0.6 Y 0.4 Rh 3.85 Ru 0.15 B 4 polycrystalline have been studied for the first time. It was shown that σ (T) near T c is well described by Aslamazov-Larkin fluctuation theories, demonstrating a 3D-2D crossover with increasing temperature. According to the crossover temperature, the coherence length along the c-axis with ξ c (0) = (2.67 ± 0.02) Å is determined. The range of superconducting fluctuations is rather narrow and amounts to ΔT fl = 0.5 K. The obtained temperature dependence of the parameter Δ*(T) [1] has the form typical for magnetic superconductors with features at T max 154 K and a temperature of a possible structural transition at T s ~ 95K. The data obtained from the magnetic measurements made for the same sample show a direct correlation with the features observed on Δ*(T). Fig. 1. Top panel: ln(σ ) vs ln(ε) in comparison with fluctuation theories: 1-3D Aslamazov- Larkin (red straight line), 2-2D Maki-Thompson (solid blue curve), where ε is a reduced temperature. Bottom panel: d(σ )/(lnε) vs ln (ε). Temperatures T G (lnε G ) and T 01 (lnε 01 ) designate the range of superconducting fluctuations. T 0 (lnε 0 ) is a crossover 3D-2D temperature. Features at lnε, lnε Rh-Rh and ln Curie corresponds to determined interplanar distance d = 3.75 Å, distance between Rh-Rh atoms 2.85 Å and T curie =20 K, respectively. [1] A. L. Solovjov, V. M. Dmitriev, Low Temp. Phys. 35, 169 (2009).

50 48 Electronic properties of conducting and superconducting systems LOCALIZED JOSEPHSON PLASMA WAVES IN A PLATE OF LAYERED SUPERCONDUCTOR IN THE PRESENCE OF А DC MAGNETIC FIELD N. Kvitka 1, T. Rokhmanova 1,2, S.S. Apostolov 1,2, V.A. Yampol skii 1,2 1 V.N. Karazin Kharkiv National University, 4, Svobody sq., Kharkiv 61077, Ukraine 2 A.Ya. Usikov Institute for Radiophysics and Electronics NASU, 12, Proskura st., Kharkiv 61085, Ukraine kvitkanina@gmail.com Layered superconductors are periodic structures, which consist of thin superconducting layers separated by thicker insulating ones forming intrinsic Josephson contacts. The strongly anisotropic high-temperature superconductors Bi 2 Sr 2 CaCu 2 O 8+δ, YBa 2 Cu 3 O 7-δ, or La 2-δ Sr δ CuO 4 are examples of such structures. The Josephson plasma waves propagating in such materials belong to the terahertz (THz) frequency range. Nowadays, THz technology is finding use in an increasingly wide variety of applications including non-destructive evaluation and security control [1]. In this work, we study theoretically the effect of a weak external homogeneous dc magnetic field (less than the critical magnetic field H c ) on the propagation of localized plasma waves in a plate of the layered superconductor which is assumed to be embedded in a dielectric environment. The plasma waves propagate along the plate perpendicular to layers (see Fig. 1). We derive the dispersion relation for the localized waves and demonstrate that it is possible to affect the dispersion law by changing the magnitude of the dc magnetic field, which can be used to control various phenomena. In particular, we discuss the resonant enhancement of the THz wave transmission tuned by the dc magnetic field. Also, we show that the dispersion curves are nonmonotonic: they consist of both increasing and decreasing parts, that correspond to normal and anomalous dispersions, respectively. With the increase of the dc magnetic field, the dispersion curves shift towards the lower frequencies (see Fig. 2). Therefore, the top points of the dispersion curves, where the group velocity of the localized waves vanishes, can be tuned by the magnetic field. The last feature can provide the possibility to observe the internal reflection phenomenon for the localized wave propagating along the plate of the layered superconductor in the inhomogeneous dc magnetic field [2]. Fig. 1. Sketch of the setup. Here kz is the wave vector, H is the external dc magnetic field, d is the thickness of the sample. Fig. 2. Dispersion curves. Here κz is the wave vector normalized to the London penetration depth across the layers, Ω is the frequency normalized to the Josephson plasma frequency. The magnetic field H/Hc = 0.1 (solid lines), H/Hc = 0.9 (dashed lines). [1] M. Tonouchi, Nature Photon. 1, 97 (2007). [2] T. Rokhmanova, S.S. Apostolov, N. Kvitka, and V.A. Yampol skii, LTP 44, 711 (2018).

51 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine FIRST OBSERVATION OF HYPERFINE LEVEL ANTICROSSINGS IN OPTICAL SPECTRA OF A CRYSTAL 49 K.N. Boldyrev, M.N. Popova Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya st. 5, Troitsk, Moscow, , Russian Federation kn.boldyrev@gmail.com Level anticrossing (also called avoided level crossing ) plays an important role in solid state physics. This is a phenomenon when two eigenvalues of the Hamiltonian depending on a continuous real parameter (like the strength of a magnetic field) cannot become equal in value ("cross"). Physically, the anticrossing is a consequence of an interaction between subsystems of different quasiparticles. In a crystal, this can be electron-phonon, electron-magnon, phononmagnon, or hyperfine (i.e., electron-nuclear) interaction. Level anticrossing manifests itself as appearance of a gap in the spectrum of the system s excitations, it is accompanied by formation of coupled modes and by a specific quantum dynamics caused by Landau-Zener-Stückelberg transitions (which leads, in particular, to a macroscopic tunneling of magnetization [1]). We have investigated the hyperfine structure in high-resolution broad-band optical absorption spectra of a strongly diluted paramagnet 7 LiYF 4 :Ho 3+ (0.1 at.%) in external magnetic fields parallel to the tetragonal symmetry axis of the crystal lattice [2,3]. For the first time the direct anticrossings of hyperfine levels in optical spectra of a crystal was demonstrated. Analysis of the spectral envelopes corresponding to transitions between the electron-nuclear sublevels of crystal-field non- Kramers doublets and singlets of the Ho 3+ ions, based on the microscopic model of the electronic 4f 10 configuration, allowed us to retrieve information on the hyperfine structure of electronic singlets, nuclear quadroupole interactions, and random lattice strains. The width of the distribution function for random strains in the studied sample was obtained from a comparison of the simulated and measured envelopes of optical transitions in the region of anticrossings with Δm =0. Gaps from 0.01 to 0.06 cm -1 (300 MHz 1.8 GHz) were observed and confirmed by model calculations at the Δm = 2 anticrossings of hyperfine sublevels of the Г 34 doublets split by a magnetic field. We show that hyperfine level anticrossings can be used to build efficient Λ and V systems for optical quantum memory. Electron-nuclear states with nuclear spin projections m and m + 2 mixed at these anticrossings can be used to build an effective Λ or V three-level system with equal optical transition probabilities in two legs of the system, for applications in optical information technologies. Financial support by the Russian Foundation for Basic Research under Grant No , by the Grant of the President of the Russian Federation МК is acknowledged. [1] R. Giraud, W. Wernsdorfer, A. M. Tkachuk, D. Mailly, and B. Barbara, Phys. Rev. Lett. 87, (2001). [2] M.N. Popova, K.N. Boldyrev, Optical Materials 63, 101 (2017). [3] K.N. Boldyrev, M.N. Popova, B.Z. Malkin, N.M. Abishev, Phys. Rev. B Rap. Comm. 99, (R) (2019).

52 50 Electronic properties of conducting and superconducting systems MAGNETIC PROPERTIES OF RCoO 3 COBALTITES (R = La, Pr, Nd, Sm, Eu). EFFECTS OF HYDROSTATIC AND CHEMICAL PRESSURE A.A. Lyogenkaya 1, G.E. Grechnev 1, A.S. Panfilov 1, I.P. Kobzar 1, V.O. Pashchenko 1, L.O. Vasylechko 2, V.M. Hreb 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, Kharkiv, Ukraine 2 Lviv Polytechnic National University, Lviv, Ukraine lyogenkaya@ilt.kharkov.ua In this work we studied the effects of temperature and hydrostatic pressure on magnetic susceptibility of RCoO 3 cobaltites (where R=La, Pr, Nd, Sm and Eu). The Co 3+ ions have an electronic 3d 6 configuration and can be in the low-spin (LS, S =0), intermediate spin (IS, S =1) and high-spin (HS, S =2) states. The energy gap between these states can be quite small and the spin state can vary with temperature and pressure. This leads to significant changes of electric, magnetic, and transport properties. The main aim was to explore dependence of the spin state of cobalt ions in these compounds on temperature and changes of the unit cell volume both under pressure and under lanthanide contraction along the RCoO 3 series. Fig. Dependence of the total energy on magnetic moment of Co3+ ion calculated at the theoretical equilibrium volume for LaCoO3. The energies are given relative to the ground state LS (M = 0). Inset: the volume dependence of the energy difference between the IS and LS states. We investigated the magnetic susceptibility of RCoO 3 cobaltites with R=La, Pr, Nd, Sm, and Eu in the temperature range K, and also under applied hydrostatic pressure of up to 2 kbar at fixed temperatures T=78 and 300 K. The obtained experimental results are analyzed with the use of the two-level model in terms of a change in population of the excited state of Co +3 ions under the action of temperature and pressure. The values of the excitation energy Δ in LaCoO 3 and its pressure derivative dδ/dp, resulting from analysis of the experimental data, are supplemented by the corresponding theoretical estimates obtained by the DFT + U calculations. Specifically, the fixed spin moment method was employed to obtain a volume dependence of the total energy difference between the Co +3 spin states of LaCoO 3 (see Fig.). In our opinion, the obtained volume dependence of Δ is the main source of the temperature dependence of this parameter due to the effect of thermal expansion. We acknowledge partial support of the Ukrainian Ministry of Education and Sciences under project DB/Feryt, N 0118U This work was performed using computational facilities of grid-cluster ILTPE of the NASU.

53 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine INFLUENCE OF THE COULOMB INTERACTION ON THE LONDON PENETRATION DEPTH IN AN ENSEMBLE OF SPIN POLARONS IN CUPRATE HTSCS 51 K.K. Komarov 1, D.M. Dzebisashvili 1,2 1 Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Krasnoyarsk, , Russia 2 Reshetnev Siberian State University of Science and Technology, Krasnoyarsk, , Russia constlike@gmail.com It is known that the unusual properties of cuprate high-temperature superconductors (HTSC) are due to the strong electron correlations, which, in particular, make it possible to understand the strong coupling between the charge and spin degrees of freedom in these materials. The spinpolaron approach [1], which strictly takes into account the indicated strong spin-fermion coupling, has been very successful in describing both the normal (N) and superconducting (SC) properties of hole-doped cuprate HTSCs. The spin-polaron approach is based on the spin-fermion model [2] (SFM), the projection technique [3] and, most importantly, considers the localized spin subsystem on copper ions in the SU(2)-invariant spin liquid quantum state. One of the important stages in the development of the spin polaron concept was the description of the Cooper instability in the ensemble of spin polarons with the d-wave pairing [1]. A significant achievement of this concept was the fact that the Coulomb interaction between holes on the nearest oxygen ions does not effect the d-wave superconductivity in cuprates, because the Fourier transform of this interaction falls out of the equation for the corresponding order parameter [4]. Analyzing the competition of superconducting d- and s-phases, it was established in work [5] that s-wave superconductivity does not occur in an ensemble of spin polarons, since the equation for the order parameter of this symmetry has no nontrivial solutions. This paper is devoted to the calculation of the London penetration depth λ with influence for the Coulomb repulsion within the spin-polaron approach in cuprate HTSCs. Using the previously developed method [6] for calculating the response of an ensemble of spin polaron quasiparticles to a uniform vector potential A q=0, we calculated the temperature and concentration dependences λ. It is shown that taking into account the Coulomb repulsion between holes on oxygen ions, which was not taken into account in [6], removes the need to artificially underestimate the value of the superexchange integral to achieve a satisfactory agreement between the theoretical and experimental dependences of the λ -2 (T) function in cuprate HTSCs. The work was financially supported by the Russian Foundation for Basic Research (RFBR) (project no ) and by the program of the Presidium of the Russian Academy of Sciences No. 12 "Fundamental problems of high-temperature superconductivity". The work of K.K. Komarov was supported by the grant of the President of the Russian Federation (projects MK and MD ) and the RFBR and partly by the Government of Krasnoyarsk Region and the Krasnoyarsk Region Science and Technology Support Fund (projects no , , ). [1] V. V. Val'kov, D. M. Dzebisashvili, A. F. Barabanov, Phys. Lett. A 379, 421 (2015). [2] A. F. Barabanov, L. A. Maksimov, G. V. Uimin, JETP Lett. 47, 622 (1988). [3] R. Zwanzig, Phys. Rev. 124, 983 (1961); H. Mori, Prog. Theor. Phys. 33, 423 (1965). [4] V. V. Val'kov, D. M. Dzebisashvili, et al., JETP Lett. 103, 385 (2016). [5] V. V. Val'kov, D. M. Dzebisashvili, et al., JETP 125, 810 (2017). [6] D. M. Dzebisashvili, K. K. Komarov EPJ B 91, 278 (2018).

54 52 Electronic properties of conducting and superconducting systems THREE SPECTROSCOPY REGIMES OF TWO-LEVEL SYSTEM D.S. Karpov 1,2, S.N. Shevchenko 1,3, U. Hübner 2, E. Il'ichev 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv 61103, Ukraine 2 Leibniz-Institut für Photonische Technologien e.v., Albert-Einstein-Straße 9, Jena, Germany 3 V. N. Karazin Kharkiv National University, Svobody Sq. 4, 61022, Kharkiv, Ukraine karpov@ilt.kharkov.ua We investigate a theoretical model to describe two-level system coupled to multimode transmission line resonators. This model has been developed in the frame of the circuit quantum electrodynamics (cqed) and related with available experimental data, and it might be useful for description of future experiments in cqed. This work opens the door for understanding physical processes in the qubit-resonator system interaction, which is the important research for future progress in quantum simulations or quantum computation processes. Our consideration is quite general and can be applied to other types of qubit-resonator systems, including semiconductor qubits, for concreteness we concentrate on most perspective qubit type transmon [1]. Further experiments in this area require a theoretical description of the processes taking place [2, 3]. Focus was on investigating the semiquantum approximation for such system. In previous papers, we obtained simplified but transparent analytic expressions for the transmission coefficient in the semiclassical approximation, which ignores the qubit-resonator correlations [4]. Such a semiclassical approach is useful, but its validity should be checked. For this reason, we further develop our calculations by taking into account the qubit-resonator correlators. Depending on the driving amplitude (Rabi frequency) and the characteristic measurement frequency, three regimes are observed. The first one is weak-driving regime, or quantum regime. This is a regime where ground and excited qubit states are monitored. The second one is a crossover regime, or the semi-classical regime [5]. And the last one is the strong-driving regime, or classical regime, where the qubit states are equally populated, which thus can also be referred to as the superposition. [1] G. Wendin, Rep. Prog. Phys. 80, (2017). [2] A. N. Sultanov, D. S. Karpov, Y. S. Greenberg, S. N. Shevchenko, A. A. Shtygashev, Low Temp. Phys. 43, 799 (2017). [3] C. K. Andersen, A. Blais, New J. Phys. 19, (2017). [4] S. N. Shevchenko, D. S. Karpov, Phys. Rev. Appl. 10, (2018). [5] D. S. Karpov, G. Oelsner, S. N. Shevchenko, Y. S. Greenberg, E. Il'ichev, Low Temp. Phys. 42, 189 (2016).

55 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine PARACONDUCTIVITY OF PSEUDOGAPPED SUPERCONDUCTORS 53 I. Poboiko 1,2,3,4, M. Feigel man 3,2 1 Skolkovo Institute of Science and Technology, Moscow, , Russia 2 National Research University Higher School of Economics, Moscow , Russia 3 L. D. Landau Institute for Theoretical Physics, Chernogolovka , Moscow region, Russia 4 Condensed Matter Physics Laboratory, National Research University Higher School of Economics, 20 Myasnitskaya St., Moscow, , Russia poboiko@itp.ac.ru We study the Aslamazov-Larkin (AL) paraconductivity [2] for a model describing a strongly disordered two- or three-dimensional superconductor close to the superconductor-insulator transition (SIT), which exhibit a large pseudogap a gap in the single-particle excitation spectrum emerging due to localized nature of single-electron wavefunctions and BCS pairing between electrons [3]. We show that the Gaussian fluctuations of the Cooper-pair fluctuations is effectively described by the time-dependent Ginzburg-Landau theory, and the corresponding paraconductivity is twice larger that the classical AL result at the same є = (T T c ) / T c. Upon decreasing the temperature, the Gaussian approximation is violated by the local fluctuations of pairing fields that become relevant at characteristic temperature scale є 1. This scale appears to be parametrically larger than the width є 2 of the thermodynamical critical region determined via the Ginzburg criterion, є 2 є 1 d. We argue that within the intermediate region є 2 є є 1, paraconductivty still follows the AL power law, albeit with another (yet unknown) nonuniversal numerical prefactor. At further decrease of the temperature, all kinds of fluctuation corrections become strong at є є 2 ; in particular, conductivity occurs to be strongly inhomogeneous in the real space. [1] Igor Poboiko, Mikhail Feigel man, Phys. Rev. B 97, (2018). [2] L. G. Aslamazov, A. I. Larkin, Sov. Phys. - Solid Sate 10, 875 (1968). [3] M. V. Feigel man, L. B. Ioffe, V. E. Kravtsov, E. Cuevas Ann. Phys. (NY) 325, 1390 (2010).

56 54 Electronic properties of conducting and superconducting systems ULTRAFAST VORTEX DYNAMICS IN SUPERCONDUCTORS: FROM LOCAL INSTABILITY TO SUPERSONIC VELOCITIES V.M. Bevz 1, A.I. Bezuglyj 1, V.A. Shklovskij 1, R.V. Vovk 1, E. Begun 2, R. Sachser 2, M. Huth 2, O.V. Dobrovolskiy 1,2 1 Physics Department, V. Karazin National University, Kharkiv, Ukraine 2 Physikalisches Institut Goethe University, Frankfurt am Main 60438, Germany zeuslan@gmail.com The dynamics of Abrikosov vortices in superconductors is usually limited to a vortex velocity v* ~1 km/s above which samples abruptly transit into the normal state. Near the critical temperature T c, this is because of the flux-flow instability induced by a reduction of the viscous drag coefficient due to quasiparticles leaving the vortex cores and causing their shrinkage (the Larkin-Ovchinnikov (LO) mechanism [1,2]). While the LO theory and all its refinements [1-4] rely upon a uniform spatial distribution of vortex velocities, the measured (mean) value of the instability velocity v m * is always smaller than the maximal possible value of v*. This is because of the distribution of vortex velocities in the ensemble of moving flux quanta never reaching the δ-functional shape. While it has recently been suggested [5] to use the quasiparticle energy relaxation time deduced from v* for assessing the suitability of superconducting materials for fast single-photon detection, the major problem consists in the underestimation of the ultimate v* value due to a rather broad v-distribution. In our work, we present two approaches for tailoring narrow v-distributions that allow for speeding up vortices up to supersonic velocities. In the first group of experiments, we address the effect of uncorrelated disorder on the instability velocity v* and demonstrate that a factor-of-two higher v* values can be achieved in Nb films with flat morphology and weak isotropic pinning as compared to Nb films with grained morphology. The observed crossover from instability jumps in a linear section of I-V curves for the grained Nb films to jumps preceded by a nonlinear upturn for the Nb films with a smooth surface is analyzed in terms of the recently developed theory [6] of local flux-flow instability. In the second group of experiments, we study the effect of correlated disorder on the fluxflow instability in superconducting Nb/ ferromagnetic Co hybrid structures in which Co layers are either continuous or periodically interrupted. In the latter case, a periodic array of 300 nm-spaced Co nanostripes was directly written by focused electron beam induced deposition [7]. By guiding magnetic flux quanta at a tilt angle of 15 with respect to the Co nanostripes, we accelerate vortices up to the first space velocity [8], that exceeds v* in the reference as-grown Nb films by an order of magnitude and is only a factor of five smaller than the maximal vortex velocities reported so far [9]. We argue that such high values of v* appear in consequence of a collective dynamic matching effect when all vortices move in the channels with the same pinning strength and exhibit a very narrow distribution of v. This is yet another example of how the well-known vortex guiding effect [10] unveils novel prospects for investigations of vortex matter at ultrafast velocities. [1] A. I. Larkin and Yu. N. Ovchinnikov, J. Exp. Theor. Phys. 41, 960 (1975). [2] A. I. Larkin and Yu. N. Ovchinnikov, Nonequilibrium superconductivity, (Elsevier, Amsterdam, 1986) p [3] A I. Bezuglyj and V. A. Shklovskij, Physica C 202, 234 (1992). [4] V. A. Shklovskij, A. P. Nazipova, and O. V. Dobrovolskiy, Phys. Rev. B 95, (2017). [5] M. Caputo, C. Cirillo, and C. Attanasio, Appl. Phys. Lett. 111, (2017). [6] A I. Bezuglyj et al., submitted. [7] M. Huth, F. Porrati, O. V. Dobrovolskiy, Microelectron. Engineering , 9 (2018). [8] O. V. Dobrovolskiy et al., [9] L. Embon et al., Nat. Commun. 8, 85 (2017). [10] V. A. Shklovskij and O. V. Dobrovolskiy, Phys. Rev. B 74, (2006).

57 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 55 ANISOTROPY AND VACANCY EFFECTS IN ELECTRONIC PROREPTIES OF NbSe 2 & RELATED STRUCTURES I.S. Bondar, S.B. Feodosyev, I.A. Gospodarev, V.A. Sirenko B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine ibondar@ilt.kharkov.ua Structure inhomogeneties are known to increase resistivity, e.g. under deformation, due to scattering effects. However, an ample evidence of enhanced conductivity is presented for highly anisotropic structures, like niobium dichalcogenides, graphenes, basic lanthanum manganite oxide when vacancy defects are introduced. A general description of this phenomena is given, based on detailed investigation of hexagonal modification diselenide. A set of measurements is reasonably explained by growth of DOS maximum and its shift towards Fermi energy level due to destruction of electron bonds, independently of the route of vacancy formation, - either by chemical substitution, or electron irradiation.

58 56 Electronic properties of conducting and superconducting systems POINT-CONTACT INVESTIGATION OF TOPOLOGICAL INSULATOR SnTe N.V. Gamayunova, O.E. Kvitnitskaya, A.V. Terekhov, Yu.G. Naidyuk B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine Tin telluride (SnTe) is a famous object of intense investigation in the fundamental physics and potential application as thermoelectric energy converters and electronic devices. Along with this the recent theoretical prediction has shown that a narrowgap semiconductor SnTe belongs to the topological crystalline insulator group [1]. Topological crystalline insulators are new states of matter with non-trivial crystal symmetry-protected topological order. These materials demonstrate an insulator behaviour in the bulk with conducting states on the surface. The experimental evidence for the topological crystalline insulator phase in SnTe was presented by ARPES study [2]. In SnTe, the topologically protected metallic surface states are protected by the mirror symmetry of the crystal [2]. The band inversion in SnTe is also responsible for the observed surface states [2]. The study of SnTe as superconductors has been less straightforward. Subsequent theoretical calculations for the case of the high-pressure phase in SnTe demonstrate a peak superconducting transition temperature T c = 7.16 K, which is in excellent agreement with the experimental value of 7.5 K [3]. The superconductivity has been observed in In-substituted SnTe. It was found the bulk onset superconductivity for Sn 0.6 In 0.4 Te with T c = 4.7 K and T zero c = 3.5 K in [4], the two-band superconductivity in Sn 1 x In x Te (x= ) with s-symmetries of the order parameters in bands and values 2Δ 1 /kt c = 3.5 ± 0.9 and 2Δ 2 /kt c = 7 ± 1 in [5], and T c = K for low-dimensional nanostructures In x Sn 1-x Te (x = ), including nanowires and nanoribbons in [6]. 2dV/dI (rel.un.) SnTe - Cu R = 4 T (K) V (mv) Fig. 1 - Temperature series of dv/di(v) spectra of SnTe-Cu PCs. Here we present the study of SnTe compounds by point-contact spectroscopy [7]. We measured dv/di derivatives of I V characteristics of SnTe point contacts (PCs) in the temperature range between 2 and 10 K. The PCs were formed using the needleanvil technique by touching a sharpened thin In or Cu wire to the cleaved surface of the bulk sample. The typical dv/di spectra show the metallic behavior with "V" or "U"-shaped zero bias minimum (Fig.1) at the lowest measurement temperatures. The intensity of the observed minimum ranged from several to 50%. The minimum becomes less intense with increasing the temperature and disappears at T = K, which was typical for both cases of SnTe-In and SnTe-Cu PCs. This temperature behavior of the observed minimum on dv/di spectra can be connected with the superconducting state in the investigated sample and requires the following studies. [1] T.H. Hsieh et. al., Nat. Commun. 3, 982 (2012). [2] Y. Tanaka et. al., Nature Phys. 8, 800 (2012). [3] D. Zhou et. al., J. Phys. Chem. C 117 (23), (2013). [4] G. Balakrishnan et. al., Phys. Rev. B 87, (R) (2013) [5] Yu.I. Gorina et. al., Physics of Solid State, 59, no. 10, 1918 (2017). [6] P. Kumaravadivel et. al., APL Mater. 5, (2017). [7] Yu.G. Naidyuk and I.K. Yanson, Point-Contact Spectroscopy (New York: Springer, 2005).

59 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine SUPERCONDUCTING FLUX QUBIT AND QUTRIT: COMPARISON AND POSSIBLE APPLICATIONS M.E. Holub 1, O.G.Turutanov 2, А.А. Soroka 3, V.Yu. Lyakhno 2, V.I. Shnyrkov 4 1 V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, 61022, Ukraine 2 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 3 National Science Center Kharkiv Institute of Physics and Technology, Akhiezer Institute for Theoretical Physics, 1 Akademicheskaya Str., Kharkiv 61108, Ukraine 4 Kyiv Academic University, Academician Vernadsky Blvd., 36, Kiev 03142, Ukraine pivo.marija95@gmail.com The level of modern technologies enables fabrication of artificial quantum systems with relatively large lifetime of their quantum states (decoherence time). This opens a possibility for creation of a quantum computer and quantum communication systems in the near future. For this sake, superconducting qubits represent probably the most promising technology [1]. The phase, charge, flux qubits and transmon are the different branches with their intrinsic advantages and drawbacks. The experimental realization of these is a difficult task [1] solved in a small number of research groups in the world. Here we focus on the common properties of and the difference between the flux qubit and flux qutrit [2] which enable applications other than quantum computer cell. These macroscopic quantum systems are often called "artificial atoms" and show superposition of two (for qubit) or three (for qutrit) quantum states, respectively. Principally, they are superconducting loops with one (like in RF SQUID) or three (like in Mooij s qubit [3]) Josephson junctions cooled to a low enough temperature. In this work we make quantum-mechanical calculations for energy spectrum of the flux qubit and flux qutrit at various parameters of the loop and Josephson junction and analyze the behavior of curvature of the base superposition level defining so-called quantum inductance. The strong nonlinear dependence of the quantum inductance on external magnetic flux in the qubit can be used for detecting small changes in the magnetic flux (in the range of a few thousandth of the magnetic flux quantum). More important, this ultrasensitive detector is non-dissipative, so it can be an ideal readout device for measuring qubit quantum states without destructive back action. The quantum inductance in the qutrit alternates (changes the sign) making it a good candidate for a coupler [4], an important element in full architecture of the quantum computer. Also, the parameters of the flux qubit are calculated with the energy spectrum suitable for detection of a single microwave photon. [1] M. H. Devoret, J. M. Martinis, Implementing Qubits with Superconducting Integrated Circuits. In: H.O. Everitt (eds) Experimental Aspects of Quantum Computing (Springer, Boston, MA., 2005). [2] V. I. Shnyrkov, A. A. Soroka, and O. G. Turutanov, Phys. Rev. B 85, (2012). [3] C. H. van der Wal, A. C. J. ter Haar, F. K. Wilhelm, R. N. Schouten, C. J. P. M. Harmans, T. P. Orlando, S. Lloyd, J. E. Mooij, Science 290, (2000). [4] A. A. Soroka, V. I. Shnyrkov, J. Low Temp. Phys. 172, 212 (2013). 57

60 58 Electronic properties of conducting and superconducting systems EFFECT OF JOSEPHSON JUNCTIONS ASYMMETRY ON THE CRITICAL CURRENT OF A QUANTUM INTERFEROMETER V.P. Koverya, S.I. Bondarenko, V.N. Fenchenko, A.V. Krevsun B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine koverya@ilt.kharkov.ua In recent years, more and more attention has been paid to the use of SQUIDs as elements of computer engineering [1]. One of the important directions of such application is the creation of superconducting devices that convert analog electrical quantities into their discrete values. Such discrete conversion of analog values of current and magnetic field can be provided by the structure proposed by us [2-4]. It is an asymmetric superconducting quantum dc interferometer, shunted by a relatively large superconducting inductance. The interferometer is made in the form of a clamped point contact niobium-niobium. A mathematical model of quantum processes in the asymmetric dc interferometer of the ultralow inductance L H is constructed. The critical current of the interferometer and the structure as a whole was determined by the method of uncertain Lagrange multipliers by finding the extremum of the auxiliary function F: I F a sin a I b sin b a b La I a sin a Lb I b sin b (1) I a I b 2 0 where I a, I b are critical currents of contacts a and b, L a, L b are inductances of contacts a and b, Ф 0 is flux quantum,, are phase jumps of the wave functions at the contacts a and b, is Lagrange * a * b multiplier. Function F consists of the sum of the critical currents of the contacts of the interferometer and the condition for the unambiguity of the wave function when traversing the contour of the interferometer. As a result of numerical calculation, the critical current of such interferometer is I C I sin I sin (2) a * a b * * where a, b are among the solutions that determine the extremum in the values of the critical current. The developed method allows us to calculate the critical current values using only the interferometer inductance values. This is important if it is impossible to measure the quantization area of the interferometer, as is the case with its microscopic dimensions typical for clamped contacts. In addition, the discreteness condition of the current transition from the interferometer to the shunt inductance is determined: 2 L0 IC 2 L 0 * * I a sin a Ib sin b 1, (3) 0 0 where L 0 =L a +L b. The model was verified by comparing the calculated parameters of the model with the experimentally measured values. [1] H. Toepfer, News Letter on Superconducting Electronics, 5, 1 (2010). [2] V. P. Koverya, S. I. Bondarenko, A. V. Krevsun, N. М. Levchenko, I. S. Bondareko, Low Temp. Phys. 36, 605 (2010) [Fiz. Nizk. Temp. 36, 759 (2010)]. [3] V. P. Koverya, A. V. Krevsun, S. I. Bondarenko, N. М. Levchenko, Low Temp. Phys. 38, 35 (2012) [Fiz. Nizk. Temp. 38, 44 (2012)]. [4] S. I. Bondarenko, V. P. Koverya, A. V. Krevsun, L. V. Gnezdilova, Low Temp. Phys, 41, 179, (2015) [Fiz. Nizk. Temp. 41, 235 (2015)]. * b

61 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine SQUID WITH WEAK LINKS MILLED BY FOCUSED ION BEAM 59 S.I. Bondarenko 1, V.P. Koverya 1, A.V. Krevsun 1, U. Hübner 2, E.V. Il ichev 2, R. Sachser 3, M.l. Huth 3, O.V. Dobrovolskiy 3 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 Leibniz Institute of Photonic Technology, Jena, Germany 3 Physikalisches Institut Goethe University, Frankfurt am Main, Germany Dobrovolskiy@Physik.uni-frankfurt.de Magnetic characterization of small spin systems, such as nanoparticles, nanowires and single molecule magnets, have fueled the development of sensors for single-particle detection and imaging with improved performance [1]. Miniature magnetometers based on micro-hall bars and micro- and nanosquids [2] allow for measurements of the magnetic stray fields emanting from micro- and nano-objects. While the sensitivity of Hall sensors deteriorates rapidly as they are reduced to the submicron size, miniaturized SQUID-based sensors can theoretically reach quantum-limited resolution [1]. In addition, from the SQUID voltage oscillations two important superconductor parameters can be deduced the superconducting energy gap [3] and the magnetic penetration depth λ [4]. In this work, we employed focused Ga ion beam (FIB) milling for the fabrication of weak links in SQUIDs made of 100 nm-thick Nb films with litographically defined 1 μm x 10 μm rectangular loops, Fig. 1(a). The milling was done in a dual-beam scanning electron microsope (SEM) FEI Nova Nanolab 600 and we have notably overcome the routinely achieved resolution of 50 nm [5]. In particular, weak links with lateral sizes smaller than 15 nm have been fabricated, Fig. 1(b), while the best resolution achieved is better than the state-of-the-art limit of 10 nm. The SQUIDs are superconducting below T c = 8.15 K and have critical currents I between 0.5 and 1 ma at T = 0.5 T c. A further characterization of the devices was done in magnetic fields applied normal to the substrate and revealed voltage oscillatations with a close-to-expected period of 0.2 mt (2 Oe), see Fig. 1(c). While several improvements are yet to be done to optimize the devices' parameters, the prospects of using the FIB milling technique for the fabrication of on-chip microsquid circuitry are evident. Fig. 1. SEM image of the Nb SQUID (a) and a closed-up image of one of its weak links (b). The voltage-field oscillations of the SQUID (c) exhibit a close-to-expected periodicity of 0.2 mt. [1] M. J. Martínez-Pérez and D. Koelle, NanoSQUIDs: Basics & recent advances in Superconductors at the Nanoscale, (Walter De Gruyter Inc., Berlin, 2017). [2] M. J. Martínez-Pérez et al., Nano Lett. 18, 7674 (2018). [3] S. I. Bondarenko et al., Low Temp. Phys. 41, 179 (2015) [Fiz. Nizk. Temp. 41, 235 (2015)]. [4] S. I. Bondarenko et al., Low Temp. Phys. 44, 184 (2018) [Fiz. Nizk. Temp. 44, 244 (2018)]. [5] O.V. Dobrovolskiy et al., Appl. Phys. Lett. 112, (2018).

62 60 Electronic properties of conducting and superconducting systems SUPPRESSION OF ORDER-DISORDER TRANSITION IN HAFNIUM- DOPED YBaCuO COMPOUNDS S.N. Kamchatnaya 1, Yu.V. Litvinov 2, R.V. Vovk 2, L.A. Kotvitskaya 2 1 Ukrainian State University of Railway Transport, 7 Feuerbach sq., Kharkiv, 61050, Ukraine 2 V. N. Karazin Kharkiv National University, 4 Svobody sq., Kharkiv, 61022, Ukraine kamchatnayasn@gmail.com This paper presents the results of studies of the effect of Hf impurities on the magnetoresistive characteristics of YBaCuO ceramic compounds in the region of the transition to the superconducting state. A radiographic research of the structure and phase composition of the YBa 2 Cu 3 O 7-δ ceramic samples depending on hafnium additions showed that the initial sample has an orthorhombic perovskite-type structure with lattice parameters: a=3.8348ǻ, b=3.8895ǻ, c= ǻ. As a result of our measurements, it was found that with an increase in the content of hafnium additives, the phase composition of the samples changes. The amount of the initial orthorhombic phase decreases, and the proportion of the orthorhombic phase with increased lattice parameters increases. The temperature dependences of the electrical resistivity in the basal ab-plane ρ ab (T), measured at H = 0, and resistive transitions to the superconducting state at different magnetic fields from H = 0 to 12 T were obtained. According to the dependences, as the temperature decreases from 300 K, ρ (T) decreases almost linearly up to a certain characteristic temperature T* 141 K. Below this temperature, the experimental points begin to deviate downward from the linear dependence, indicating the appearance of excess conductivity Δσ. The application of a magnetic field leads to a significant broadening and blurring of the superconducting transition. As is known from Refs. [1, 2], the presence in the system of strong pinning centers, contributing to the blurring of the kink and the transition from the phase of an ordered vortex lattice to a phase of the so-called vortex or Bragg glass, can result in such an effect, which is caused by the accommodation of the vortex systems to the chaotic potential of pinning. [1]. Thus, it can be concluded that the phase transition immediately near T c is satisfactorily described by the Aslamazov-Larkin three-dimensional model for layered superconducting systems. The application of a constant magnetic field to YBa 2 Cu 3 O 7- samples with an admixture of hafnium, in contrast to similar, pure samples, leads to a blurring of an additional paracoherent transition on the temperature dependences of excess conductivity in the base ab-plane in the region of resistive transitions to the superconducting state. This may be due to the effect of bulk pinning, due to the presence in the structure of the experimental sample the phase inclusions formed when a hafnium impurity is introduced. As a result, at temperatures below the critical T <T c, a dynamic phase transition in the form of a vortex liquid vortex lattice is suppressed and a vortex liquid vortex Bragg glass is formed. [1] R. V. Vovk, Z. F. Nazyrov, M. A. Obolenskii, I. L. Goulatis, A. Chroneos, V. M. P. Simoes, Journal of Alloys and Compounds 509, 4553 (2011). [2] W. K. Kwok et.al., Phys. Rev. Lett. 69, 3370 (1992).

63 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine DETECTION OF THE CHARACTERISTICS OF THE BUBBLE BOILING REGIME IN HELIUM BY A SUPERCONDUCTING FILM IN A RESISTIVE STATE S. Kruglov, A.S. Pokhila, A.G. Sivakov B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine pokhila@ilt.kharkov.ua It is known that an increase in the current through a superconductor in a resistive state inevitably leads to overheating of the sample, which in turn distorts the type of current voltage characteristics (IVC) and leads to thermal instability and breakdowns in the IVC. Moreover, when the sample is cooled with liquid helium, the heat dissipation can reach a value sufficient for the formation of bubbles. On the other hand, the formation of bubbles provides efficient heat extraction and its characteristics are important for many technical applications in cryotechnology and cryomedicine. The paper proposed a method for detecting helium bubbles by measuring the voltage drop on a film bridge in a resistive state with a phase-slip mechanism. Due to the fact that the oscillations of the order parameter in time arise as a result of the phase-slip mechanism, the average superconducting current has a constant value at constant temperature, and the increase in the transport current is due to the normal component. In this case on the current voltage characteristics there is a linear section with a differential resistance equal to the normal and excess current. Since the excess current is strongly dependent on the temperature, the voltage on the sample for a given value of the transport current will reflect the change in the sample temperature. During the formation of bubbles the heat sink will change in time, so the output voltage will reflect the processes of formation of bubbles, their transformation and breakaway from the substrate. In this case, the heat can be increased or decreased by varying the resistance of the detector due to a change in the geometric dimensions and the heat transparency of the film with the substrate. The dimensions of the sensor can be chosen from the view of commensurability with the dimensions of the bubble and there is a chance to study the dynamics of the development of a single bubble. The paper presents the oscillation features of the current voltage characteristics for films of different geometry and materials as well as experimental data confirming the fact that these features are associated with the bubbling boiling of liquid helium. 61

64 62 Electronic properties of conducting and superconducting systems EVOLUTION OF A FOUR-LEVEL QUANTUM SYSTEM M.A. Nakonechnyi 1, A.I. Ryzhov 1,2, S.N. Shevchenko 1,2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, 61022, Ukraine mykhail.nakonechnyi@gmail.com Mesoscopic objects such as a system of two qubits or a double quantum dot are important objects in quantum engineering [1, 2, 3]. These devices behave as quantum four-level systems. In our work, the evolution of such system was simulated by the numerical solution of the basic kinetic equation in the form of Lindblad equation. Original interference patterns of the dependences of time-averaged level populations on the parameters of the system were obtained. The equilibrium stationary level populations were found using the rotating-wave approximation without considering the transient dynamics. Comparison of numerical simulation with experimental interferograms in Refs. [2, 4] is the method for determining the spectrum, system parameters, temperature, relaxation coefficients. Therefore, matching the results and obtaining accurate data on the system can help in describing further experiments on the evolution of the multi-level quantum systems, such as two qubits and double quantum dots. [1] E. A. Temchenko, S. N. Shevchenko, A. N. Omelyanchouk, Phys. Rev. B 83, (2011). [2] M. F. Gonzalez-Zalba et al., Nano Lett. 16, 1614 (2016). [3] S. N. Shevchenko, A. I. Ryzhov, F. Nori, arxiv: [4] A. Chatterjee et al., Phys. Rev. B 97, (2018).

65 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 63 MAGNETISM AND MAGNETIC Magnetism MATERIALS and Magnetic Materials

66

67 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 65 MAGNETIC PROPERTIES AND H-T PHASE DIAGRAMM OF TbCr 3 (BO 3 ) 4 A. Bludov 1, Yu. Savina 1, M. Kobets 1, V. Khrustalyov 1, V. Savitsky 1, V. Pashchenko 1, T. Zajarniuk 2, M.U. Gutowska 2, A. Szewczyk 2, I. Kolodiy 3, N. Kuzmin 4, V. Mal tsev 4, N. Leonyuk 4 1 B. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkov, Ukraine 2 Institute of Physics, Polish Academy of Sciences, Warsaw, Poland 3 National Science Center «Kharkov Institute of Physics and Technology» Kharkov, Ukraine 4 Lomonosov Moscow State University, Moscow, Russia bludov@ilt.kharkov.ua Terbium chromium borate TbCr 3 (BO 3 ) 4 belongs to the large family of compounds with a general chemical formula RM 3 (BO 3 ) 4 (R = lanthanides or Y; M = Al, Ga, Sc, Fe or Cr). The majority of crystals of this family has the structure of huntite mineral CaMg 3 (CO 3 ) 4, which crystallizes in the trigonal crystal system with R32 space group [1, 2]. The main elements of the crystal structure are spiral chains of sharing edges MO 6 octahedra along the c axis. The RO 6 prisms and the planar triangular BO 3 groups combine the chains into a 3D structure. These compounds attract considerable attention of scientists over last several decades primarily due to their optical, magnetoelectric and magnetoelastic properties [3]. By the X-ray studies, the R32 structure of our TbCr 3 (BO 3 ) 4 crystals was verified and lattice parameters were determined at the room temperature (a = Å and c = Å). Magnetic, thermal and magnetoelectrical properties of TbCr 3 (BO 3 ) 4 single crystal have been investigated. The temperature dependences of magnetic susceptibility χ(t), the field dependences of magnetization M(H), and the temperature dependences of specific heat C p (T) have been measured by using the SQUID magnetometer MPMS-XL5 QD (2 300 K, up to 5 T) and the QD PPMS system (2-300 K, up to 9 T). The external magnetic field has been applied along and perpendicular to the crystallographic axis c. Investigations of electrical polarization have been carried out by means of a homemade setup in magnetic field up to 3.5 T at 4.2 K only for H c. The TbCr 3 (BO 3 ) 4 undergoes phase transition into antiferromagnetically ordered state at T N = K. Spontaneous spin-reorientation phase transition from the easy-plane (EP) antiferomagnetic state to the easy-axis (EA) one occurs in the vicinity of 5 K. The EA state exists in a limited range of temperatures (below 5 K) and magnetic fields (below 0.5 T for H c). An intermediate magnetic phase might exist slightly above 5 K and in fields lower than 0.02 T. Electrical polarization appears in the EP and paramagnetic states and is absent in the EA state. The H-T phase diagram of TbCr 3 (BO 3 ) 4 for H c has been constructed based on the experimental data. [1] N. I. Leonyuk, L. I. Leonyuk, Progr. in Crystal Growth and Charact. 31, , (1995). [2] V. S. Kurazhkovskaya, E. A. Dobretsova, E. Yu. Borovikova, V. V. Mal tsev, N. I. Leonyuk, Journal of Structural Chemistry. 52, Issue 4, , (2011). [3] A. M. Kadomtseva, Yu. F. Popov, G. P. Vorob ev, A. P. Pyatakov, S. S. Krotov et al., Low Temp. Phys. 36, 511 (2010).

68 (emu/(g*oe)) (emu/(g*oe)) 66 Magnetism and magnetic materials MAGNETIC PROPERTIES OF GREIGITE NANOPARTICLES OF DIFFERENT SIZES M. Pashchenko, P. Veverka, O. Kaman, J. Hejtmanek Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Praha, , Czech Republic Magnetite, Fe 3 O 4, is the oldest known magnetic material and its nanoparticles have received intense investigation as the clinically used contrast agent for MRI, as a unique tracer for MPI and as a universal magnetic carrier for drug delivery, separation and catalysis. This work is devoted to greigite, Fe 3 S 4, the sulfur analog of magnetite. Similarly, to magnetite, greigite exhibits also an inverse spinel structure and ferrimagnetic arrangement. Considering the low toxicity of greigite particles, they seem to be a promising material not only for high-performance lithium ion batteries[1], but possibly also for medical applications, such as cancer treatment by magnetic hyperthermia, MRI and magnetically guided drug delivery [2]. For all these applications, the size of particles represents a crucial parameter, and at the same time the size of particles influences their fundamental physical properties. The aim of our study is to determine the dependence of magnetic properties of hydrothermally prepared greigite nanoparticles on their size. The two samples studied in detail were characterized by the mean size of crystallites d XRD 30 nm and d XRD 120 nm according to powder XRD and by a rather broad size distribution according to TEM. The investigation of magnetic behavior was carried out by SQUID magnetometry and selected magnetic measurements are shown in figures below FC ZFC nm Field 100 Oe 30nm 120nm FC ZFC 30nm Temperature (K) Fig.1. ZFC-FC susceptibilitiesfor Fe 3 S 4 Fig.2. Temperature stability of the FC samples with d XRD 30 nm and 120 nm. susceptibility at 100 Oe during cooling and heating in the range K. Measurements of ZFC-FC curves (Fig.1) show that both the samples did not reach the superparamagnetic state at room temperature and remained predominantly in the blocked state. Furthermore, cooling-heating-cooling scans up to 390 K at magnetic field 100 Oe (Fig.2) evidence that the susceptibility depends on the history of the two samples, and for the larger particles the dependence is less pronounced. This observation might be attributed to the gradual transition of particles between the blocked and the superparamagnetic state at elevated temperatures Temperature (K) [1] Q. D Li, Q. L. Wei, W. B. Zuo, L. Huang, W. Luo, Q. Y. An, V. O. Pelenovich, L. Q. Mai, and Q. J. Zhang, Chem. Sci., 8(1), (2017). [2] M. Feng, Y. Lu, Y. Yang, M. Zhang, Y. J. Xu, H. L. Gao, L. Dong, W. P. Xu, and S. H. Yu, Sci Rep,3, Article number: 2994 (2013).

69 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine THE INTENSITY OF f - f ELECTRONIC TRANSITIONS IN A CRYSTAL PrFe 3 (BO 3 ) 4 DURING ELECTRON-PHONON INTERACTION K.N. Boldyrev 1, M.N. Popova 1, B.Z. Malkin 2 1 Institute of Spectroscopy, Russian Academy of Sciences, Fizicheskaya st. 5, Troitsk, Moscow, , Russian Federation 2 Kazan Federal University, Kremlyovskaya st. 18, Kazan, , Russian Federation kn.boldyrev@gmail.com Earlier, in the works [1-3], the method of terahertz spectroscopy revealed and investigated new effects due to electron-phonon interaction in an antiferromagnetic crystal. In the spectra of a crystal PrFe 3 (BO 3 ) 4, splitting of a nondegenerate low-frequency phonon of A 2 symmetry was observed due to its interaction with is close in energy the 4f-electron excitation of the Pr 3+ ion [1]. As a result, a bound electron-phonon mode is formed, in which, as the temperature decreases, repulsion and energy transfer between its quasi-phonon and quasi-electron components are observed. It should be noted that isolated 4f-electronic excitations are not visible in the reflection spectra due to the small oscillator strength. Modeling based on the theory of electron-phonon interaction allowed us to find the interaction constant. When a PrFe 3 (BO 3 ) 4 single crystal is placed in an external magnetic field along the easy axis of magnetization, a gap appears in the spectrum of quasi-electron excitations in an arbitrarily weak field [2]. It was shown [2] that the frequencies of coupled electron-phonon excitations in a magnetic field up to 30 T are successfully simulated on the basis of equations obtained in the framework of the theory of electron-phonon interaction, with the interaction constant independent of the field, previously found in [1]. The temperature and field behavior of the intensities of the components of the coupled electron-phonon mode has not yet been quantitatively considered. Even qualitatively, the field behavior of the intensities of the split quasi-electron components when the crystal was placed in an external magnetic field remained incomprehensible. In the present work, the problem of a bound electron-phonon mode is considered by the method of Green functions. The frequencies of the coupled excitations are found as poles of the spectral representation of the Green function. 67 ( ) ( ) i G G t e t dt (1) QQ 1 2 The intensity of the electric dipole absorption at frequency ω is proportional to the imaginary part of function (1). The simulation made it possible to quantitatively describe the observed experimental data on the behavior of the coupled electron-phonon mode in a PrFe 3 (BO 3 ) 4 crystal in fields up to 30 T. The crystals used in the work were grown by L.N. Bezmaterny at the Institute of Physics. L.V. Kirensky SB RAS in Krasnoyarsk. Financial support by the Russian Foundation for Basic Research under Grant No is acknowledged. [1] K.N. Boldyrev, T.N. Stanislavchuk, A.A. Sirenko, L.N. Bezmaternykh, M.N. Popova, Phys. Rev. B Rapid Comm. 90, (R) (2014). [2] K.N. Boldyrev, T.N. Stanislavchuk, A.A. Sirenko, D. Kamenskyi, L.N. Bezmaternykh, M.N. Popova, Phys. Rev. Lett. 118, (2017). [3] M.N. Popova, K.N. Boldyrev, Phys. Usp. 62 (3) (2019). QQ

70 Intensity derivative (arb.units) 68 Magnetism and magnetic materials SPIN WAVE EIGENMODES IN PERPENDICULARLY MAGNETIZED SUBMICRON TRIANGULAR DOTS Y.I. Kharlan, E.V. Tartakovskaya, P.V. Bondarenko, O.Y. Saliuk, V.O. Golub Institute of Magnetism of NAS of Ukraine and MES of Ukraine, 36-b Acad. Vernadskogo Ave., Kyiv, 03142, Ukraine The modern nanolithography provides a possibility to create regular arrays of magnetic superstructures with large numbers of submicron elements. Among these systems, two-dimensional (2D) arrays of magnetic dots on nonmagnetic substrates are of special interest for spintronics and magnonics applications. Here the method of nanosphere lithography was used to produce hexagonal arrays of nickel islands of h=70 nm height on silicon substrate [1]. The shape of nickel islands is close to regular triangular truncated pyramids with the base side a=270 nm. The supposition about triangular shape islands was used in the proposed theoretical model. The standard electron spin resonance spectrometer Bruker ELEXSYS E500 operating at 9.86 GHz was used to record ferromagnetic resonance spectra at room temperature. Three practically equidistant resonance peaks were observed in the experiment (Fig.1). The distance between them was of about 500 Oe. Such type of spectrum is quite similar to which was observed in cylindrical ferromagnetic dots [2] H (Oe) Fig. 1. Experimental ferromagnetic resonance spectrum. Spin wave eigenmodes in triangular dots in perpendicular saturating magnetic field have been investigated both experimentally and theoretically. Although observed modes are quite similar to modes in thin magnetic submicron dots of different shapes (circular, rectangular, etc.), the well known theoretical approach [2-4] can not be applied in our case because of strong lateral variation of the demagnetizing fields. The triangular membrane transverse vibration functions [5] were taken as the eigenfunctions of the unperturbed Schrödinger equation, the spin wave Landau-Lifshitz equation had been reduced to. The developed theoretical approach provided a good agreement with the experiment. [1] J. C. Hulteen, R. P. Van Duvne, J. Vac. Sci. Technol. A. 13(3), , (1995). [2] G. N. Kakazei, P. E. Wigen, K. Y. Guslienko, V. Novosad, A. N. Slavin, V. O. Golub, N. A. Lesnik, and Y. Otani, Appl. Phys. Lett. 85, 443 (2004). [3] K. Yu. Guslienko, A. N. Slavin. J. Appl. Phys. 87, , (2000). [4] X. Zhou, E. V. Tartakovskaya, G. N. Kakazei, A. O. Adeyeye, PRB 96, , (2017). [5] B. R. Seth, Proc.: Math. Sci. 12.5, (1940).

71 H a, koe H a, koe X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 69 FMR FEATURES OF Fe 3 S 4 NANOPARTICLES AT T = 300K IN COMPARISON WITH LOW TEMPERATURE DATA O. Kravchuk 1, A. Vakula 1,2, M. Pashchenko 3, P. Veverka 3, J. Kuličková 3, O. Kaman 3 1 Kharkiv National University of Radio Electronics, 14 Nauka Ave, Kharkov, 61166, Ukraine 2 O.Ya. Usikov Institute for Radiophysics and Electronics of National Academy of Sciences of Ukraine, 12 Proskura St., Kharkov, 61085, Ukraine 3 Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Praha 6, Czech Republic flouer.filia@gmail.com Fe 3 S 4 nanoparticles (NP) are interesting not for the paleomagnetism application only, but they are interesting in materials science too (LIBs - lithium ion batteries) [1]. Fe 3 S 4 NP can also be used in oncological hyperthermia treatment and magnetic drug delivery treatment due to its high selfheating capacity (43 C / 8 min) and low toxicity (1 mg / ml) [2]. Also, it is known that Fe 3 S 4 does not have a magnetic phase at low temperatures. The aim of this work is analysis of FMR in Fe 3 S 4 NP at T = 4.2K and T=300K, and also comparison of these properties for NP with different diameter. Two samples of Fe 3 S 4 NP with diameters d = 30 nm and d = 100 nm were studied. The samples were prepared as alloy of Fe 3 S 4 nanoparticles and adhesive phenol butyral (BP). The samples shaped as spheres with a diameter of 0.8 mm. The low frequency (f = 9.99 GHz) experiments were carried out in the field scanning mode. The shift of the resonance field for Fe 3 S 4 NP with d = 30 nm and d = 100 nm relative to resonance field for DPPH (reference sample) was observed. We assume that shift is due to the presence of the total magnetic anisotropy field H a. The difference in H a between Fe 3 S 4 NP d = 30 nm (H a 30 ) and d = 100 nm (H a 100 ) depicted on Fig.1 0 T=300K, f=9.99 GHz DPPH 1 T=4.2K, f=72.5 GHz NP Fe 3 S 4 d=100nm -0,5-1 NP Fe 3 S 4 d=30nm NP Fe 3 S 4 d=100nm 0-1 NP Fe 3 S 4 d=30nm DPPH a) Fig.1 Bar graphs of H a values for Fe 3 S 4 with d=30 nm and d=100 nm at T=300K (a) and T=4.2K (b) We found, that at T=4.2K H a 30 = 855 Oe; H a 100 = 1003 Oe and at T=300K H a 30 = 716 Oe; H a 100 = 541 Oe. For the sample Fe 3 S 4 NP with d=100 nm the field H a suffer a sign reversal for in T = K. This indicate the presence of some kind of magnetic phase transition in the above mentioned temperature area T = K. Authors are grateful to Dr. J. Hejtmanek (Institute of Physics ASCR, Prague, Czech Republic) for providing samples and counseling for research and Prof. S.Tarapov (IRE NASU, Kharkov, Ukraine) for discussions. [1] Guowei Li at al., Chem.Mater., 26, pp (2014) [2] Yo-Sheng Chang at al., Journal of Colloid and Interface Science, 363, pp (2011). b)

72 70 Magnetism and magnetic materials NONLINEAR DYNAMICS OF THE SPIN CHAIN WITH LONG-RANGE INTERACTION IN THE CONTINUUM LIMIT P.V. Bondarenko, B.A. Ivanov Institute of Magnetism of NAS of Ukraine and MES of Ukraine, 36-b Acad. Vernadskogo Ave., Kyiv, 03142, Ukraine One of the simple physical implementations of the magnetic dipole chain is the array of the submicron magnetic dots organized in linear chain and determined by rather high spatial regularity. The dots have no direct contact between each other; therefore the sole source of their interaction is the magnetic dipolar interaction. Solitons and solitary localized waves in this system are interesting and important objects of the basic physics of magnetism and can have the applied applications [1]. Usually condensed matter systems have a periodic structure thus the problems of nonlinear perturbations are described by discrete nonlinear equations [2,3]. The coaction of the nonlinearity, dispersion and discreteness causes a set of nonlinear excitations such as discrete breathers, solitons and solitary waves. The standard solving approach is to reduce the discrete problem to the corresponding continual one [4]. The exception is a small number of exactly solvable discrete nonlinear problems [5]. Significant deviations in this case are observed only when a wavelength or a size of localized mode is close to the lattice constant of the system. The continuum limit is well applicable for the systems with short-range interaction, since in this case the sum of the expansion terms is always finite. The transition to continual description is much more complicated in the case of strong dipoledipole interaction. Then the lattice sums diverge already at the second order expansion terms. In this report we consider an alternative method of obtaining the continual limit in the 1D spin chain with dipole interaction based on the long-wave asymptotics of dipole sums [6]. It was shown that the obtained in continuum approximation kink solution is in a good agreement with the results of direct numerical simulations and both results differ significantly from the approximation of the nearest neighbors (i.e. Gochev s solution). The analysis of the obtained in continuum approximation dynamical soliton solution shows non-analytical behavior of the soliton form in the neighborhood of its center. This feature of the form function arises from the logarithmic dependence determined by the long-range interaction as in the case of non-analyticity of the magnon spectrum in the long-wave range. The appearance of weakly non-analytical solutions is a characteristic feature of systems with long-range interaction and can not be obtained in finite cutting off interaction range [6]. [1] R. P. Cowburn, M. E. Welland, Science, 287, 1466 (2000). [2] S. Flach, C. R. Willis, Phys. Rep. 295, 181 (1998). [3] R.L. Pylypchuk, Y. Zolotaryuk, Low Temp. Phys. 41, 733 (2015). [4] A.M. Kosevich, B.A. Ivanov and A.S. Kovalev, Phys. Rep. 194, 117 (1990). [5] I.G. Gochev, JETP Lett, 26(3), (1977). [6] P.V. Bondarenko, A.Y. Galkin, B.A. Ivanov and C.E. Zaspel, Phys. Rev. B 81, (2010).

73 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine MAGNETIC RESONANCE AND SHORT-RANGE MAGNETIC ORDER IN ErAl 3 (BO 3 ) 4 CRYSTAL S.N. Poperezhai 1, V.A. Bedarev 1, D.N. Merenkov 1, M.I. Kobets 1, A.A. Zvyagin 1, T. Zajarniuk 2, A. Szewczyk 2, M.U. Gutowska 2, I.A. Gudim 3 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 Institute of Physics, Polish Academy of Sciences, Al. Lotnikуw 32/46 PL Warsaw, Poland 3 Kirensky Institute of Physics, Akademgorodok 50, bld. 38, Krasnoyarsk, Russia Sergey.Poperedjay1986@gmail.com The rare-earth alumoborates have become of considerable interest for detailed evaluation due to their valuable luminescent and non-linear properties. In addition, a giant magnetoelectric effect was observed in these crystals [1]. It was shown that rare-earth alumoborates can be promising materials for magnetic cooling [2]. Erbium alumoborate ErAl 3 (BO 3 ) 4 is interesting representative of this family. The multiplet 4 I 15/2 (S=3/2, L=6, J=15/2) is the ground state of the Er 3+ ion in this trigonal non-centrosymmetric crystal. The multiplet 4 I 15/2 is splitted by the crystal field and the ground doublet is separated by~46 cm -1 from the first excited doublet [3]. Therefore, only one absorption line, associated with transitions between two levels of the main doublet, should be observed in the EPR spectrum. However, a low-intensity additional resonance line was previously detected in the EPR spectrum of ErAl 3 (BO 3 ) 4 crystal at 4.2 K [4]. The goal of the present work is to clarify the cause of particularities in the EPR spectrum of ErAl 3 (BO 3 ) 4. A triplet structure of the main line and a low-intensity additional line had been observed in the EPR spectra at 4.2 K. The triplet structure occurs at an inclined magnetic field direction from the trigonal axis c of the crystal. In general, the measurements data indicate the observation of spincluster resonance [5] which is caused by the existence of magnetically ordered groups of rare-earth ions. In the framework of this model, the appearance of an additional low-intensity line is associated with the flipping of a couple of moments, and the triplet structure arises due to the flips of one magnetic moment in the cluster. The calorimetric method was used to detect the magnetic clusters in ErAl 3 (BO 3 ) 4. It was shown that the magnetic subsystem of the crystal inputs a significant contribution to the specific heat capacity at low temperatures (T 4.2 K). Thus, calorimetric studies confirm the existence of magnetic clusters in ErAl 3 (BO 3 ) 4. These clusters are due to the establishment of short-range magnetic order in the crystal. The additional absorption line and the triplet structure of the main line have been observed in the EPR spectra and both result from such clusters presence. [1] K.C. Liang, R. Chaudhury, B. Lorenz, Y.Sun, L. Bezmaternykh, V.Temerov, C. Chu, Phys. Rev. B. 83, (2011). [2] M. I. Pashchenko, V. A. Bedarev, D. N. Merenkov, A. N. Bludov, V. A. Pashchenko, and S. L. Gnatchenko, T. Zajarniuk and A. Szewczyk, V. L. Temerov Low Temp. Phys. 43, 631 (2017) [3] A.V. Malakhovskii, V.V. Sokolov, I.A. Gudim, J. Alloys and Comp., 698, 364 (2017). DOI: /j.jallcom [4] V. A. Bedarev, D. N. Merenkov, M. I. Kobets, S. N. Poperezhai, S. L. Gnatchenko, and I. A. Gudim, Low Temp. Phys. 44, 863 (2018). [5] M. Date, M. Motokawa, Phys. Rev. Letters 16, 1111 (1966); J. Phys. Soc. Japan 24, 41 (1968). 71

74 72 Magnetism and magnetic materials LOW-TEMPERATURE THERMODYNAMICS OF FINITE SPIN-1/2 XX CHAINS WITH XXZ IMPURITIES O.S. Dzhenzherov, E.V. Ezerskaya V.N.Karazin Kharkiv National University, Dept. of Physics 4 Svoboda sq., Kharkiv, 61022, Ukraine adzhenzherov@gmail.com Low dimensional magnetism is of big interest for the theoretical study because of numerous experimental data related to really existing magnetic crystals formed by weakly interacting clusters, chains or planes. This work is devoted to the theoretical study of quantum stationary states, and thermodynamic properties of finite spin-1/2 XX-chain with an XXZ impurity link, and finite XX-chain with XXZ impurity spin situated on one of the intermediate lattice sites. These models are of interest, as an example of so-called broken chain effect. For special cases of XX impurity, both models are exactly solvable [1, 2], and the second model is exactly solvable in case of Ising-type impurity also. The models` Hamiltonians have the following form: and N N 1 z x x y y z z x x y y B Sn J Sn Sn 1 Sn Sn 1 J0 J n0 n0 1 1 Sn S 0 n0 1 Sn0S n0 1 n 1 n 1; n n0 H ˆ g H ( ) S S ( ), (1) N N 1 z z z z z x x y y 0 B n 0 B Sn J0 n0 n0 1 n0 1 J Sn Sn 1 Sn Sn 1 n 1 n 1 ( n n0 ) ( n n0 1; n n0 ) Hˆ g HS g H S ( S S ) ( ) J ( S S S S S S S S ) x x y y x x y y 1 n0 1 n0 n0 1 n0 n0 n0 1 n0 n0 1 We studied the stationary states with one inverted spin for general case of both models. For XX impurities for (1) and (2) models we found the exact dispersion equations and analytical inequalities for the values of the critical model parameters describing the appearance of local energy impurity levels. For model (2) in case of Ising-type impurity we also performed the same calculations. We analyzed thoroughly above inequalities for these limiting cases. The field and temperature dependences of the main thermodynamic characteristics were simulated numerically by exact diagonalization study and analytically in special cases. It was shown that the field dependence of the heat capacity has a complex nature with numerous minima and maxima. The field dependence of the magnetization at very low temperatures may have finite jumps associated with impurity levels. At low temperatures, the average value of the impurity spin in case of rather strong antiferromagnetic ZZ interaction with the main XX chain has a jump at the critical field. We associate this jump with an impurity spin flip along the direction of the magnetic field. OSD acknowledges the support of the State Fund of fundamental research of Modern Physics (via grant 33683). EVE acknowledges the support of the VolkswagenStiftung, Germany (via grant ). [1] A. A. Zvyagin, Quantum Theory of One-Dimensional Spin Systems (Cambridge Scientific Publishers, Cambridge, 2010). [2] E. Lieb, J.Schults, and D. Mattis, Ann. Phys. 16, 407, (1961). (2)

75 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine EXCHANGE BIAS PHENOMENA IN NEW MULTIFERROIC BiFe 0.5 Sc 0.5 O 3 PEROVSKITE 73 A.V. Fedorchenko 1, E.L. Fertman 1, V.A. Desnenko 1, V.V. Shvartsman 2, D.C. Lupascu 2, S. Salamon 3, H. Wende 3, A.I. Vaisburd 4, A. Stanulis 5,6, R. Ramanauskas 5, N.M. Olekhnovich 7, A.V. Pushkarev 7, Yu.V. Radyush 7, D.D. Khalyavin 8, A.N. Salak 9 1 B.Verkin Institute for Low Temperature Physics and Engineering of NASU, Kharkiv, Ukraine 2 Institute for Materials Science & CENIDE, University of Duisburg-Essen, Essen, Germany 3 Faculty of Physics & CENIDE, University of Duisburg-Essen, Duisburg, Germany 4 V. N. Karazin Kharkiv National University, Kharkiv, Ukraine 5 Department of Electrochemical Materials Science CPST, Vilnius, Lithuania 6 Energy Safety Research Institute (ESRI), Swansea University, Swansea, United Kingdom 7 Scientific-Practical Materials Research Centre of NASB, Minsk, Belarus 8 ISIS Facility, Rutherford Appleton Laboratory, Oxfordshire, United Kingdom 9 Department of Materials and Ceramic Engineering, University of Aveiro, Aveiro, Portugal fedorchenko@ilt.kharkov.ua Multiferroic BiFe 0.5 Sc 0.5 O 3 perovskite compound prepared by high-pressure synthsis exists in two metastable modifications, namely an antipolar orthorhombic Pnma polymorph and the polar orthorhombic Ima2 one. The exchange bias (EB) effect has been found in the polar phase of BiFe 0.5 Sc 0.5 O 3 obtained by annealing of the high-pressure stabilized antipolar phase (see Fig.1). The exchange field, H EB, and the coercive field, H C, were found to be strongly dependent on temperature and strength of the cooling magnetic field, H cool (see Fig.2). H EB increases with increasing the cooling magnetic field and reaches the maximum value of about 1 koe at 5 K and H cool = 20 koe. H EB decreases with increasing temperature and vanishes above the Néel temperature T N 220 K with the disappearance of the long-range magnetic ordering. The EB effect is associated with the weak ferromagnetism driven by the Dzyaloshinskii-Moriya antisymmetric exchange interactions revealed in the BiFe 0.5 Sc 0.5 O 3 perovskite. The effect is promising for the application in electronics as it is large enough and tunable by the cooling magnetic field and temperature. Fig.1. Magnetic hysteresis loops for the polar BiFe 0.5 Sc 0.5 O 3 compound measured after the FC procedure at 50, 150, and 200 K. Inset: an enlarged view of the central region of the hysteresis loops at 50 K measured after ZFC and FC (H cool = 20 koe). Fig.2. Cooling field dependence of the exchange bias field H EB (H cool ) at 5 K for the BiFe 0.5 Sc 0.5 O 3 compound. The lines between points are guides to the eye. Inset: a cooling field dependence of the coercive field H c (H cool ). This work was supported by the TUMOCS project (EU Horizon 2020 grant No ). The part of this work done in the University of Aveiro was developed within the scope of the project CICECO-Aveiro Institute of Materials (POCI FEDER , and UID/CTM/50011/2013). Financial support by the DFG via FOR 1509 (WE2623/13) and SFB 1242 (project A5) is gratefully acknowledged.

76 e 11 (H)/e 11 (0) 74 Magnetism and magnetic materials ELASTIC, PIEZO AND MAGNETOELECTRIC PROPERTIES OF HoAl 3 (BO 3 ) 4 M.P. Kolodiazhnaia 1, I.V. Bilych 1, K.R. Zhekov 1, G.A. Zvyagina 1, V.D. Fil 1, I.A. Gudim 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 L.V. Kirensky Institute for Physics, Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, , Russia kolodyazhnaya@ilt.kharkov.ua The HoAl 3 (BO 3 ) 4 attracts considerable attention due to its outstanding magnetoelectric characteristics. The electric polarization stimulated by the magnetic field reaches record values of ~ 5000μC / m2 (T ~ 4K, H ~ 6 T). There is a sufficient number of publications covering various physical characteristics of HoAl 3 (BO 3 ) 4, but there are clearly insufficient data on its elastic, piezoelectric and magnetoelastic properties. This message partially closes this gap. 1. Elastic moduli (GPa) and piezomodule (C/m 2 ) С were measured at frequencies of ~ 55 MHz 11 С 33 С 44 С 12 C 14 e 11 and T=77K.Their values are given in table Magnetopiezoelectric effect and magnetocapacitance These terms imply the dependence of the piezoelectric response and permittivity on the state of the magnetic subsystem, as well as on the external magnetic field. The source of this behavior is the significant asphericity of the rare-earth ion. The external fields (elastic and electric) do not change, in the first approximation, the magnitude of the resulting magnetic moment, but lead to its rotation and the corresponding modulation of the interaction with the crystalic field. From qualitative considerations, it is clear that a higher magnitude of the deformation or the electrical susceptibility of rotation realizes at a smaller magnetic anisotropy.in the previously studied ferroborates, due to the small anisotropy in the base plane, the discussed effects are well pronounced only in easy-plane phases. Due to the increased rigidity in the relation to the output of magnetic vectors from the base plane, their planar components are in equal conditions. As a result, the dependence of the magnitudes of the effects on the H direction in the base plane is symmetric with respect to its rotation from the x axis to the y axis. Such a behaviour is well confirmed in experiments. The situation is completely different in HoAl 3 (BO 3 ) 4. The orientation dependence is completely asymmetric (see fig.1a,b). We believe that this behavior is caused by an increased softness relative to the output of the magnetic vectors from the base plane a ) T=1.7K H, T xx (H)/ xx (0) b) T=1.7K H,T The thermodynamic potential has to include the terms responsible for the interaction of external fields with the z component of the magnetic moment. For example, the magnetoelectric 2 2 interaction with the field Ex can be represented as F... a E m m a E ( m m )... Here, ai Fig 1. Magnetic field dependencies of the piezomodule (a) and permittivity(в) for different directions H, H - the angle between H and the x axis. x z y x x y are the susceptibilities of rotation in the base plane and perpendicular to it, mi are the direction cosines of the moment M of the REM ion. It results in the following a sin 2 H 4 a sin H xx( H) (0) (φ and θ are the angular coordinates of M). The third term F / F / describes the asymmetric dependence of xx on the orientation of H in the base plane.

77 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine SPIN-WAVE RESONANCES IN INDIVIDUAL CIRCULAR NANOMAGNETS 75 N.R. Vovk 1, S.A. Bunyaev 2, D. Navas 2, P. Gruszecki 3, M. Krawczyk 3, R. Sachser 4, M. Huth 4, K.Yu. Guslienko 5,6, G.N. Kakazei 2, O.V. Dobrovolskiy 1,4 1 Department of Physics, V. N. Karazin Kharkiv National University, Kharkiv, Ukraine 2 IFIMUP-IN/Department of Physics and Astronomy, University of Porto, Porto, Portugal 3 Faculty of Physics, Adam Mickiewicz University, Poznan, Poland 4 Physikalisches Institut, Goethe University, Frankfurt am Main, Germany 5 Departamento Física de Materiales, Universidad del País Vasco UPV/EHU, San Sebastián, Spain 6 IKERBASQUE, the Basque Foundation for Science, Bilbao, Spain nikolayvovk94@gmail.com Magnetic properties of nano-elements are known to differ substantially from those of the bulk materials they are made from [1]. At the same time, the knowledge of the saturation magnetization M s and the exchange constant A ex governing the magnetodynamic response of nanomagnets is pivotal for the functionality of various magnon-spintronic applications ranging from magnetic sensing to data storage and microwave communications [2, 3]. While an analytical description of the spin-wave dynamics in micro- and nanosized magnetic elements of arbitrary shape is barely feasible, because of the inhomogeneity of the internal demagnetizing field, in the few cases of simplest symmetry, represented for instance by circular disks and infinite stripes, the spin-wave eigenfrequencies can be calculated explicitly. In particular, the analytical model [4] has been proven to be very successful for the description of spin-wave resonances in Py and Ni nanodisk arrays [5]. Here, we employ a dipole-exchange spin-wave dispersion equation from Ref. [5] to deduce M s and A ex for individual Co-Fe nanodisks of submicrometer radii. The Co-Fe nanomagnets were directly written by focused electron beam-induced deposition [6] and studied by broadband ferromagnetic resonance spectroscopy with an external magnetic field applied along the normal to sample plane. The finite disk radius leads to the quantization of the in-plane spin-wave vector and gives rise to resonance drum modes with circular zero-order Bessel-function profiles. Experimentally, we were able to record spin-wave spectra from individual Co-Fe disks with thickness L = 40 nm and radius R = 100 nm. The analytical theory has been generalized for large aspect ratios L/R 0.5 and found to agree well with experimental data. Furthermore, a good agreement with Mumax 3 numerical simulations [7] has been revealed, thereby validating the simulation framework for more complex Co-Fe circular nanostructures such as a "nano-volcano" composed of a nano-ring overlying a nano-disk. In all, we demonstrate that the proposed approach of probing magnetic parameters of individual nano-elements by spin-wave spectroscopy is especially valuable for the characterization of magnetic materials that are unavailable in large arrays or in bulk form. Furthermore, the deduced magnetic parameters can be used in simulations of spin-wave spectra in circular nano-elements with a more complex shape, for which an analytical description of the spin-wave eigenfrequencies is not available. [1] S. Sangiao et al., Beilstein J. Nanotechnol. 8, (2017). [2] A.V. Chumak, V Vasyuchka, A. Serga, B. Hillebrands, Nat. Phys. 11, 453 (2015). [3] D. Grundler, Nat. Nanotechnol. 11, 407 (2016). [4] B.A. Kalinkos and A.N. Slavin, J. Phys. C 19, 7013 (1986). [5] G. N. Kakazei et al., Appl Phys Lett 85, 443 (2004). [6] M. Huth, F. Porrati, and O. V. Dobrovolskiy, Microelectronic Engineering, , 9 (2018). [7] A.Vansteenkiste et al., AIP Advances 4, (2014).

78

79 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 77 OPTICS, PHOTONICS AND OPTICAL Optics, SPECTROSCOPY Photonics and Optical Spectroscopy

80

81 Normalized intensity or absorption Normalized intensity or absorption X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine PHOTOPHYSICS OF HALOGEN SUBSTITUTED ASYMMETRICAL PORPHYCENES AT THE LIQUID NITROGEN TEMPERATURE 79 A.Yu. Kharchenko, A. Listkowski, J. Waluk Institute of Physical Chemistry, Polish Academy of Sciences Kasprzaka 44/52, Warsaw, Poland akharchenko@ichf.edu.pl Porphycenes, constitutional isomers of porphyrin are more attractive than the parent molecule for investigation of tautomerization, due to lower symmetry of the inner cavity. It results in strong absorbance in the low-energy region of the visible spectrum [1]. Investigations of the properties of symmetrical porphycenes in comparison with 9-amino- or 9-acetoxy-substituted ones revealed rapid tautomerization upon excitation of the higher energy species [2]. Now we present the photophysical study of novel 9-halogen substituted porphycenes: 9-chloro- (1), 9-fluoro-2,7,12,17-tetra-tertbutylporphycene (2), and 9-fluoroporphycene (3) (1), MTHF: r.t., absorption 90 K, absorption 90 K, (emission) = 670 nm nm 1,0 hexane: (2), r.t. (excitation) = 560 nm 0,8 (3), r.t. (excitation) = 355 nm 0,6 0,4 0,2 fluorescence of trans-2 tautomers MTHF: (1), 90 K (excitation) = 560 nm 0, nm Figure 1. Left, absorption and fluorescence excitation spectra (Q bands) of 1 at room temperature in comparison with the low temperature conditions, T = 90 K; 2-methyltetrahydrofuran (MTHF) was used as a solvent. Right, the fluorescence spectra of 1, 2, and 3 at different temperatures conditions. r.t. room temperature. First, it was observed that the lowest energy peak of the absorption and fluorescence excitation spectra of all porphycenes under investigation is split due to the presence of two nonequivalent tautomers (trans-1 and trans-2). The relative ground state populations of the two trans tautomers are different for fluorine and chlorine derivatives. In order to determine relative populations and to estimate the height of the tautomerization barrier in the excited state, temperature dependence of absorption and emission was investigated. Absorption and fluorescence excitation spectra were recorded down to the liquid nitrogen temperature. As expected, narrowing of the bands is observed. More important, fluorescence from both tautomeric forms was detected. The dominant emission has a peak at about 650 nm. For 3 the small peak corresponding to the other tautomer has been already observed at the room temperature, while for 2,7,12,17-substituted porphycenes 1 and 2 it was detected only at low temperature. It should be noted that the excitation spectra of 1 are not identical at different emission wavelengths, contrary to porphycenes 2 and 3. Consequently, the rapid excited state trans-trans tautomerization occurs in the case of 9- fluoro-2,7,12,17-tetra-tert-butylporphycene and 9-fluoroporphycene, but not in 9-chloro-2,7,12,17- tetra-tert-butylporphycene. [1] J. Waluk, Chem. Rev. 117, , (2017). [2] P. Fita, M. Pszona, G. Orzanowska et al. Chem. Eur. J. 18, , (2012).

82 80 Optics, photonics and Optical spectroscopy OPTICAL SPECTROSCOPY AND POLARIZED LIGHT STUDY OF Co- BASED LAYER DOUBLE HYDROXIDES I.M. Lukienko 1, R.Yu. Babkin 2, Yu.G. Pashkevich 2, Yu.M. Kharchenko 1, D. Wulferding 3, P. Lemmens 3,4, D.E.L. Vieira 5, A.N. Salak 5 1 B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 O. Galkin Donetsk Institute for Physics and Engineering of the National Academy of Sciences of Ukraine, 46 Nauky Ave., Kyiv 03680, Ukraine 3 Laboratory for Emerging Nanometrology (LENA), TU Braunschweig, D Braunschweig, Germany 4 Institute for Condensed Matter Physics, TU Braunschweig, D Braunschweig, Germany 5 CICECO-Aveiro Institute of Materials, Department of Materials and Ceramics Engineering, University of Aveiro, Aveiro, Portugal lukijenko@ilt.kharkov.ua We report on optical absorption and polarized light microscopy studies of nano-flakes of double layered hydroxides (LDHs), expressed by the general chemical formula [M 2+ 1-xM 3+ x(oh) 2 ] x+ (A y- ) x/y mh 2 O (short version: M 2+ (n)m 3+ -A), where divalent M 2+ and trivalent M 3+ cations are Co 2+ and Al 3+, correspondingly. The layers of LDHs consist of trigonally distorted (D 3d ) octahedral layers of hydroxide OH - pairs, with the cations inside and anions A y- located between these layers. The replacement of Co 2+ ions by Al 3+ ions in some Co 2+ (OH) 6 octahedral hydroxides leads to appearance of a positively charged net, compensated by the anions located between the alternating layers. Every nanoflake consists of several hydroxide octahedral layers, which are kept together not only due to electrostatic interaction but predominately due to hydrogen bounds. A weak coupling between the layers allows intercalation of the interlayer space with different functional organic and inorganic anionic complexes. Due to this specific property, LDHs are attractive for many applications, such as bioactive nanocomposites in medicine, nanocontainers for self-healing corrosion protection, acid absorbents for air and water treatment, and others. Our studies are mainly focused on dynamics of the hydrogen bonding in a range between room temperature and liquid helium temperature, which is reflected in the variation of the d-d-optical transitions and the frequencies of the OH vibrations. We considered the Co(n)Al-LDHs with different cations ratio n = Co/Al (n = 2, 3 and 4) intercalated with either CO 3 2- or NO 3-. It was revealed from Raman scattering spectrum that an increase of n leads to attenuation of the hydrogen bond s strength. Optical absorption spectra and XRD data allowed to conclude that the hydrogen bonds subsystem remains at room temperature in a highly fluctuated dynamic state. The level of fluctuations depends on the cations ratio n. The hydrogen bonds become frozen at temperatures of liquid nitrogen and liquid helium. The energy of the optical transitions levels has been modelled within the original modified crystal field approach. Optical polarized light microscopy and Scanning transmission electron microscopy studies revealed peculiarities in the shapes of nanoflakes for LDHs with different cations ratio n. It is observed, that for LDHs with a relatively low concentration of Co (n = 2 and 3) and high anisotropy shape, the compacted nanoflakes compose optically anisotropic crystallite blocks which are well seen in a polarized microscope as conoscopic figures. At the same time, for the compound with the largest concentration of Co cations (n = 4) no conoscopic figures have been detected, because of near-spherical shape of nanoflakes and, as a result, because of their random orientation after compacting process. The research conducted at the University of Aveiro was supported by project TUMOCS. This project has received funding from the European Union s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No

83 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine LASER STIMULATED WHITE EMISSION PROCESSES IN TRANSPARENT Cr 3+,Cr 4+,Ca 2+ :YAG CERAMICS 81 M. Chaika 1, R. Tomala 1, O.M. Vovk 2, R.P. Yavetskiy 2, W. Strek 1 1 Institute for Low Temperatures and Structure Research, Polish Academy of Sciences, P.O. Box 1410, Wroclaw, Poland 2 STC Institute for Single Crystals of NAS of Ukraine,61 Nauky Ave., Kharkiv, 61103, Ukraine m.chaika@intibs.pl Cr 4+ :YAG widely used as tuneable μm lasers or passive Q-switchers for solid state lasers [1]. Moreover, the lasing efficiency of high-quality Cr 4+ :YAG crystals is no higher than 10% indicating the fact that some energy loss process of unknown origin take place in these crystals. Our results demonstrate that the Light Induced White Emission (LIWE) [2, 3] may be one of a reason of energy loss in Cr 4+ :YAG materials. We found that transparent Cr,Ca:AYG ceramics are able to generate bright LIWE at excitation power above a certain threshold. The intensity of LIWE greatly increases with increasing pumping power after exceeding the threshold 0.7W (see Fig. 1a). Further increase of laser power leads to enhancement of emission intensity. The integral intensity increases exponentially with increasing excitation power. The initial slope 3.4 would show that three or four photons are involved in the multiphoton conversion process which corresponds to energy of 3.5 ev ev. Decreasing pressure from to 0.1 mbar does not affect the emission intensity of LIWE and some kind of saturation can be observed (see Fig. 1b). Further decreasing of pressure below 0.1 mbar lead to reduce the LIWE by two orders of magnitude Fig. 1. The effect of incident light power on LIWE spectra under 1064 nm laser excitations (a), The effect of pressure on intensity of the LIWE under 3.4W 1064 laser excitations at 300 K (b). The results indicate that efficient four photon absorption processes take place. They may be the source of energy losses in Cr 4+ :YAG laser materials. Further investigations of LIWE will allow to find way to increase the laser efficiency of Cr 4+ :YAG materials. [1] Chaika, M., Dulina, N., Doroshenko, et al. Ceram. Int., 44, , (2018). [2] Strek, W., Marciniak, L., Gluchowski, P. et al. Opt. Mater., 35, (2013). [3] Strek, W., Marciniak, L., Bednarkiewicz, A., et al. Opt. express 19, , (2011).

84 Total Scattering Cross Section 82 Optics, photonics and Optical spectroscopy OPTICAL RESPONSE OF HOLLOW GOLD NANOPARTICLES L.N. Illyashenko 2, N.P. Stognii 1, O.G. Nerukh 1 1 Kharkiv National University of Radio Electronics,14 Nauky Ave., Kharkiv, 61166, Ukraine 2 O.Ya. Usikov Institute for Radiophysics and Electronics of NAS of Ukraine, 12, Ac. Proskura st., Kharkiv, 61085, Ukraine nstognii@gmail.com In this work we study optical response of noble metal nanoparticles and report how it may be controllably varied over a wide range of wavelengths. The current intense interest in gold nanoparticles is due to their Surface Plasmon Resonances (SPR) that depend strongly on the shape and size [1] of the nanoparticles. As the SPR wavelength and resonantly enhanced absorption and scattering properties also depend on the dielectric medium in which gold nanoparticle is embedded, they are useful in testing for environmental contaminants, chemical and biological liquids. Among others, hollow nanoparticles have enhanced sensitivity due to the coupling of plasmonic fields on their external and internal surfaces. With purpose to select the most promising configurations in this work the scattering characteristics as functions of optical wavelength are investigated for various hollow Au nanoparticles in different surrounding solvents, to determine their sensitivity. SPRs are identified as peaks in total scattering cross-section (Fig. 1), that is presented as a 400 nm, 700nm. It was found that SPR results in function on the excitation wavelength strongly enhanced absorption and scattering. For gold nanoparticles SPR falls in visible region of the electromagnetic spectrum, which is fundamental for their many color based applications. The effectiveness of plasmonic nanoparticles for each particular application depends strongly on their optical response at SPR, particularly: Scattered light makes it possible to identify the resonant wavelength almost precisely due to ability to distinguish the color of reflected light. Then Localized Surface plasmon resonances (LSPRs) with enhanced scattering efficiency are useful for cell and biomedical imaging as well as other applications based on light scattering. LSPR is followed by the rapid conversion [nm] Fig. 1: Scattering cross-section as function on an excitation wavelength for hollow gold nanostars with R 50nm (100 nm from tip to tip), illuminated by an electromagnetic plane wave along (0, -1) direction in various solvents r (4 5) R. of the absorbed light into heat, which may be used for selective photothermal therapy of cancer and bacterial infections. Such applications may also require low scattering losses along with a high nanoparticle light absorption. Designing a nanoparticle with optimum absorption and optimum scattering may make a dual imaging/therapy approach possible. The work is aimed at understanding relations between the sensitivity of nanoparticle [2] to the size of internal surface of the hollow Au nanoparticles, which can provide guidelines for a choice of their parameters to be used for new applications in biological sensing and imaging, medical diagnostics, drug development, photothermal therapy of cancer and bacterial infection. [1] S.K. Dondapati, T.K. Say, C. Hrelescu, T. A. Clar, F. D. Stefani, and J. Feldmann, ACS Nano. 4, , (2010). [2] P.K. Jain, and M. A. El-Sayed, J. Phys. Chem. C. 47, , (2007).

85 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine RESONANT ABSORPTION OF ELECTROMAGNETIC WAVES ACCOMPANIED BY EXCITATION OF LOCALIZED MODES WITH ANOMALOUS DISPERSION IN LAYERED SUPERCONDUCTORS 83 S.S. Apostolov 1,2, M.V. Mazanov 2, Z.A. Maizelis 1,2, N.M. Makarov 3, A.A. Shmat'ko 2, V.A. Yampol'skii 1,2 1 A.Ya. Usikov Institute for Radiophysics and Electronics NASU, Kharkiv, Ukraine 2 V. N. Karazin Kharkiv National University, Kharkiv, Ukraine 3 Benemérita Universidad Autónoma de Puebla, Puebla, Pue , México mazanovmax@gmail.com Metamaterials attract significant attention, in the main because of their unusual interaction with electromagnetic waves [1]. The negative refraction effect could be achieved in materials with uniaxial anisotropic structure in which components of the dielectric permittivity tensor have different signs (the so-called hyperbolic materials). The layered superconductors, comprising the alternating thin superconducting layers and thicker dielectric layers, could meet these criteria in a wide frequency range. Moreover, the electromagnetic excitations of the strongly anisotropic and nonlinear electron plasma in layered superconductor, the so called Josephson plasma [2], come into existence in the THz frequency range, which allows for the practical use of the layered superconductors as the main components of various photonic devices operating at this band. In the work we have studied theoretically the resonant absorption of electromagnetic THz waves of TM-polarization in a slab of layered superconductor enclosed within twofold dielectric layers, which is induced by excitation of the modes localized on the slab. This phenomenon, known as the Wood anomaly, i.e. suppression of the specular reflection, shows some unusual features when the superconducting layers of the slab are perpendicular to its boundaries, because the dispersion curves for the localized modes are non-monotonic in this geometry [3]. We have considered the bilateral symmetric and antisymmetric wave excitations of the setup, generating the symmetric and antisymmetric localized modes, respectively. The conditions for the resonant absorption and the analytical expression for the absorptance A have been deduced using the transfer-matrix method with account for weak dissipation (the dissipated energy is thought to originate from quasiparticle relaxation, and the corresponding relaxation frequencies are assumed to be small [4]). We have shown that the total absorption is attainable and have determined the corresponding values of the problem parameters. Additional computations have also shown that the most effective absorption can be attained when parameters nearly satisfy the dispersion relations, confirming the excitation of the localized modes in the slab. Further analysis has also revealed the non-lorenzian shapes of the resonant dependence of the absorptance A on the incident angle θ, when the wave frequency ω is tuned near the top point on the dispersion curve. The twin resonant peaks, which merge into a single broad peak when increasing the wave frequency, are the representative shapes of this kind, see Fig. 1. The experimental observation of such shapes in the absorptance dependence can imply the clear manifestation of the existence of the localized modes with nonmonotonic dispersion in the layered superconductors. Fig.1. Dependence of absorptance on the incidence angle for two close values of the wave frequency. [1] S.A.Maier, World Scientific Handbook of Metamaterials and Plasmonics (World Scientific, Singapore, 2017, v.1). [2] S.Savel ev, V.A.Yampol skii, A.L.Rakhmanov, F.Nori, Rep. on Progress in Phys. 73 (2010). [3] S. S. Apostolov, N. M. Makarov, and V. A. Yampol skii, Physical Review B 97 (2018). [4] Y.I. Latyshev, A.E. Koshelev, L.N. Bulaevskii, Physical Review B 68 (2003).

86 84 Optics, photonics and Optical spectroscopy NUMERICAL SIMULATION OF EELS SPECTRA OF PLASMONIC NANODIMERS ACCOUNTING FOR SPATIAL DISPERSION EFFECTS WITH THE DISCRETE SOURCES METHOD I.V. Lopushenko Lomonosov Moscow State University,Faculty of Physics, Chair of Mathematics, Leninskie Gory 1/2, Moscow , Russian Federation Despite the tremendous progress in the field of nanoplasmonics, complex plasmonic nanostructures such as dimers still present a significant challenge for both experimental and numerical characterization. Since the size of the nanoparticles (NPs) quite often is well below the Abbe diffraction limit, one typically has to rely on electron microscopy methods, including such approaches as electron energy-loss spectroscopy (EELS), to investigate these structures [1-3]. In order to better understand experimental measurements and to properly interpret the results, accurate EELS simulations are required, creating demand for flexible and reliable numerical approaches capable of efficiently modeling single NPs and NP systems [2-4]. In this work to address these problems a new mathematical model based on the hybrid scheme of the Discrete Sources Method (DSM) was developed and corresponding computer model was implemented. It enables one to successfully resolve the problem of accounting for non-local spatial dispersion effects occurring in the nanometer-scaled plasmonic dimers via Generalized Nonlocal Optical Response (GNOR) model, which is especially important in the systems with very small gap size [5-7]. At the same time the proposed approach retains such key features of the original DSM as flexibility and a posteriori error estimation [8,9]. The developed model allows to simultaneously consider several external excitations of the plasmonic nanodimer, including non-electron excitations such as plane waves, in order to obtain more information about the system and to significantly speed up computational performance. We compute electron energy loss probability and plane wave total scattering cross section as functions of incident field frequency for various dimers of spherical particles. However, the developed approach can be generally applied to study nonspherical particles. Analysis of the numerical model and corresponding simulation results will be in the main focus of the presentation. [1] F. C. Castro, V. P. Dravid. Microscopy and Microanalysis 24, 3, (2018). [2] J. A. Lloyd, S. Hock Ng, A. C. Y. Liu, Y. Zhu, W. Chao, T. Coenen, J. Etheridge, D. E. Gómez, and U. Bach. ACS Nano 11, 2, (2017). [3] S. Thomas, C. Matyssek, W. Hergert, M. Arnold, L. Kiewidt, M. Karamehmedovic, T. Wriedt. Plasmonics 11, (2016). [4] T. Wriedt, Yu. Eremin (Eds.). The Generalized Multipole Technique for Light Scattering (Springer International Publishing, 2018). [5] Y. Eremin, A. Doicu, T. Wriedt. Journal of Quantitative Spectroscopy and Radiative Transfer 217, (2018). [6] S. Raza, S. I. Bozhevolnyi, M. Wubs, N. A. Mortensen. J. Phys.: Condens. Matter 27, (2015). [7] F. J. García de Abajo. Journal of Physical Chemistry C 112, (2008). [8] I. Lopushenko. J. Phys.: Conf. Ser. 1092, (2018). [9] Yu. A. Eremin, I. V. Lopushenko. Moscow Univ. Comput. Math. Cybern. 41, 4, (2017).

87 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine MAGNETIC FIELD INDUCED PHASE TRANSITION AND THE LOW FREQUENCY DYNAMIC IN KDy(MoO 4 ) 2 85 K.V. Kutko 1, S.N. Poperezhai 1, N.M. Nesterenko 1, D.L. Kamenskii 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 High Field Magnet Laboratory (HFML EMFL), Radboud University, Toernooiveld ED Nijmegen, The Netherlands kkutko@ilt.kharkov.ua KDy(MoO 4 ) 2 exhibits the pseudo Jahn-Teller type phase transition at the low temperature (T PT 14 K), which is accompanied with the renormalization of the electronic excitation spectrum [1]. Additionally, at 4.2 K the magnetic field applied in a certain direction (along the maximal value of the g-factor, at 45 in the a-b plane) leads to the structural transformation of the crystal [2]. In this work we continue the Far-Infrared (FIR) study of the low-energy spectra [1] up to 70 cm -1 at 1.4 K in external magnetic field. At figure 1a the magnetic field dependences of the electronic excitations e1, e2, and e3 and the phonon excitation ph, obtained from experimental FIR Fourier - transmission spectra at E x c, H b, k b are shown. The magnetic field dependences for electronic excitations correspond to the transitions between Zeeman components of the ground and first excited levels (see Fig. 1b). We suppose, that in the region of intersection of electronic branches (crossover) with different J (J = 15/2 and J = 13/2) and phonon excitation with similar energy (circles in the Fig. 1) the magnetic field induced phase transition is exist. So, an external magnetic field at 1.4 K affects on the crystal in the same way, as the mixing of the two nearest components of the multiplet by Jahn-Teller interaction at 14 K, which puts the system into the symmetrical phase. The symmetry of the magnetic field induced phase is supposed the same [2], but may be other. Fig. 1. a the magnetic field dependences of low frequency excitations at E x c, H b, k b, T=1.4K; b the scheme of electronic levels in magnetic field (in the linear approximation). [1] A.A. Zvyagin, K. Kutko, D. Kamenskyi, A.V. Peschanskii, S. Poperezhai, N.M. Nesterenko, Phys. Rev. B98, (2018). [2] M. J. M. Leask, O. S. Tropper, M. L.`Wells, J. Phys. C: Solid State Phys. 14, 3481 (1981).

88 86 Optics, photonics and Optical spectroscopy FEATURES OF THE EXCITON DYNAMICS AND SELF-TRAPPING OF CARBOCYANINE J-AGGREGATES FORMED IN POLYMER FILMS А.V. Sorokin 1, I.Yu. Ropakova 1, S. Wolter 2, R. Lange 2, I. Barke 2, S. Speller 2, S.L. Yefimova 1, Y.V. Malyukin 1, S. Lochbrunner 2 1 Institute for Scintillation Materials of NAS of Ukraine, SSI Institute for Single Crystals of NAS of Ukraine, 60 Nauky ave., Kharkiv, Ukraine 2 Institute of Physics and Department of Life, Light and Matter, University of Rostock, Rostock, Germany ropakova@isma.kharkov.ua Organic materials, especially, nanostructured ones, have attracted intense research interest as a very promising subject for optoelectronic and photonic applications. Organic molecules exhibit high fluorescence efficiencies at low particle densities, a wide variety of optical properties, and are easy and cheap to process, resulting in an extreme large design flexibility, very good possibilities for integration into devices, and an impressive performance of organic materials. In active organic devices, including organic light-emitting diodes, organic photovoltaic cells, organic field-effect transistors, electrochromic devices, and organic nonlinear optics, the material is typically applied in form of thin films. Until now it was believed that solid-state samples prepared by various methods have similar spectral properties although such a statement hasn t been proved experimentally yet. The aim of the work is to compare the features of the exciton dynamics and spectral properties of TDBC dye J-aggregates formed in neutral spin-coated and charged LbL polymer films. Morphologies and spectral properties of TDBC J-aggregates formed in two different types of polymer films were studied using both time-resolved spectroscopy and optical and atomic force microscopy. It was found that the J-aggregates reveal different morphologies in the films: quasi onedimensional rod-like in the spin-coated films and two-dimensional island-like in the layered films. The TDBC J-aggregates exhibit very similar absorption and fluorescence spectra in the different films, but their fluorescence lifetimes and quantum yields differ strongly (~ 4% for spin-coated films and ~ 0.5% for layered films). Low temperature experiments reveal strong exciton selftrapping in the J-aggregates due to large exciton-phonon coupling. However, the different morphologies of the TDBC J-aggregates in the films result in different behaviors of exciton self-trapping. While in spin-coated films barrierless self-trapping is dominant, in layered films it is associated with overcoming an energy barrier. Thus, we have shown that the morphology and spectral properties of solid-state samples dramatically depend on the method of preparation.

89 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine FEATURES OF LOW TEMPERATURE LUMINESCENCE OF FULLERITE NITRIDE C 60 N X P.V. Zinoviev, V.N. Zoryansky, V.V. Meleshko B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, Prospekt Nauky, 47, Kharkiv 61103, Ukraine zoryansky@gmail.com Low temperature studies of the fullerite C 60 saturated by nitrogen in the chemical adsorption mode were carried out by the spectral-luminescent and powder x-ray diffraction method. The influence of nitrogen sorption on structural and luminescent properties of fullerite C 60 was studied for the samples prepared by the gas pressure of 30 atm and the saturation temperature above 420 С. The kinetics of nitrogen sorption was studied by using the time dependence of fullerite lattice parameter at 20 K. Significant changes of the photoluminescent characteristics of C 60 +N 2 solutions with a high impurity concentration were observed in the temperature range K. For the saturated with nitrogen above T = 450 C samples it was observed a diffusive broadening and a low-energy shift of the luminescence spectra unlike hydrogen adsorption [1]. In addition, an unusual behavior of the temperature dependence of the integrated radiation intensity was observed. This dependence was reproduced both during heating and during cooling of the sample. All this facts indicate to chemical interaction between nitrogen with fullerene molecules and formation of a new molecular material, namely, nitride fullerene С 60 N x [2]. Such behavior of photoluminescent characteristics can be resulted by the appearance of new molecular complexes at the formation of nitride fullerene. These complexes can play the role of quenching centers with a certain activation energy and lifetime. [1] P.V. Zinoviev, V.N. Zoryansky and N.B. Silaeva, Fizika Nizkikh Temperatur, 34 (6), (2008). [2] I.V. Legchenkova, К.А. Yagotintsev, N.N. Galtsov, V.V. Meleshko, Yu.Е. Stetsenko, and А.I. Prokhvatilov, Fizika Nizkikh Temperatur, 40 (8), (2014). 87

90

91 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 89 QUANTUM LIQUIDS AND QUANTUM Quantum Liquids CRYSTALS, CRYOCRYSTALS and Quantum Crystals, Cryocrystals

92

93 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine STRUCTURAL STUDIES OF CH 4 -N 2, N 2 -Kr, Ar-Kr CRYOALLOYS 91 N. Mysko-Krutik, A. Solodovnik B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine misko@ilt.kharkov.ua Solid binary cryocrystal solutions are of considerable interest for many reasons. Structure analyses of such solid solutions make it possible to obtain important information for a creation new theoretical approaches and a check of the existing models [1], including the magnitude and nature of the orientational order, phase transformations, the quadrupolar glass state. [2]. It is known that in some cases Vegard s rule and Prigogine model are insufficient and in this connection novel theories are needed. Moreover, cryocrystal solutions is known to occur in the planetary environments [3]. In the paper studies of solid Kr-Ar, N 2 СH 4, N 2 -Kr are presented. Observations were carried out in a standard electronograph EG 100A equipped with a helium cryostat. The deposition regime was chosen in order to obtain random distributions of impurity. The samples were grown in situ by condensation gaseous mixtures on Al or C substrate at T = 20K and T = 5 K and in the process of subsequent temperature change right up to sublimation of specimens. The error in the lattice parameter measurements was usually 0.1%. The gases were mixed in a special bottle at room temperature the typical waiting time of up to 5 min ensured a uniform distribution of the gases. The relative error in the intensity measurements did not exceed 7%. Detailed electron diffraction studies have been carried out for the nitrogen-krypton, methanenitrogen and argon-krypton systems. Crystallographic structure of observed phase was established. Based on analysis of the obtained diffraction patterns and the concentration dependences of the lattice parameter the region of existence of solid solutions was determined. In N 2 -CH 4 cryoalloys the limiting solubilities of the components are: methane in a nitrogen crystal is less than 6 mol%, nitrogen in solid methane is less than 35 mol%. The lattice parameters as a function both concentration and temperature are analyzed using Prigogine s theory, Vegard's rule and the cluster approach [4]. The structure of Ar-Kr alloys corresponds to fcc in the entire region of mutual concentrations. For the first time phase separation into two phases was observed in concentration interval мол % Ar. The effect of impurity particles on the orientational ordering of N 2 molecules was investigated in solutions for N 2 -based phase. The orientational order factor η was determined based on comparison between measured and calculated intensity of diffraction patterns. The influence of the composition, the deposition temperature, subsequent heating on the orientational order factor η of the N 2 molecules were studied. [1] The Physics of Cryocrystals, V. G. Manzhelii, Yu. A. Freiman, M. L. Klein, A. A. Maradudin (eds.), AIP Press, Woodbury (1997). [2] M. A. Strzhemechnyy, A. A. Solodovnik, S. I. Kovalenko, LTP, 24, 669 (1998). [3] New Horizons Update: Methane Detected; New Images of Pluto and Charon; Sunrise/Sunset Observations, Lillian Gipson(NASA), RIA NEWS, July 31, [4] A. A. Solodovnik, V. V. Danchuk, N. S. Mysko, LTP 39, 456 (2013).

94 92 Quantum liquids and quantum crystals, cryocrystals ON THE ONE THERMOMAGNETIC EFFECT IN SUPERFLUID SYSTEMS A.M. Konstantinov, S.I. Shevchenko B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine He-II is characterized by two unique properties, one of which is superfluidity and the other is often called super thermal-conductivity. The enormous increase in the effective thermal conductivity coefficient is due to the fact that heat transfer in He-II is associated with the motion of the normal component. In this case, the mass flow carried by the normal component is compensated by the mass flow carried by the superfluid component, i.e. we have a counterflow in which heat is transported by internal convection, not accompanied by mass transfer. An extremely important circumstance is the fact that the condition for the absence of mass flow should be satisfied only on average, i.e. only the area-averaged mass flux should be equal to zero. In general, the local mass flow is not vanish. Since the motion of any dielectric in a magnetic field leads to its polarization, in the presence of a magnetic field a local dipole moment in superfluid helium will be associated with a local mass flow generated by a temperature gradient T, and an average electric field may emerge outside the system. As a result, we conclude that in superfluid systems there should be a thermomagnetic effect similar to the Nernst-Ettingshausen effect in conducting systems. In the paper the laminar counterflow state of superfluid helium in a capillary in the presence of a temperature gradient and a magnetic field is considered. An expression for the electric potential outside the capillary is obtained as a function of the temperature difference at the ends of the capillary and the applied magnetic field. It is established that the electric potential substantially depends on the geometry of the sample. In particular, the potential for the elliptical capillary was calculated and it was shown that the result depends on the direction of the magnetic field with respect to the axes of the ellipsoid. The maximum value of the potential is reached in the limiting case of a slit when the magnetic field is directed across the slit.

95 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine ELECTRONICALLY-STIMULATED DELAYED DESORPTION OF PARTICLES FROM SOLID METHANE AND SOLID ARGON DOPED WITH METHANE I.V. Khyzhniy, E.V. Savchenko, S.A. Uyutnov, M.A. Bludov B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine Radiation-induced particle emission from solid CH 4 has attracted much attention because of its high effectiveness in moderation of hot neutrons. Solid methane is also of high interest for planetary and interstellar astrophysics. Although much is known about this phenomenon in solid CH 4 [1], dynamics of the particle emission remains scarcely studied. Solid CH 4 was irradiated at low T by an electron beam (1.5 kev, 3.5 macm -2 ). After irradiation during an hour we observed for the first time explosive particle emission which was correlated with a flash of the CL. Main channels of CH 4 degradation produce H atoms and CH 3 radicals. The most substantial final products of CH 4 radiolysis are H 2 and C 2 H 6 [2,3]. Their formation proceeds in the exothermic reactions which deliver the energy for particle emission. Delay in the giant burst of particles with respect to the start of irradiation indicates the need for the accumulation of defects (radiolysis products) for this effect. Interesting feature of the particle burst is its oscillatory character which requires further study. The total yield of particles desorption from solid Ar doped with CH 4 under irradiation with an electron beam was studied at 5 K. The measurements were carried out at a CH 4 concentration of 1% and 5%. The effect of explosive delayed desorption from the surface of argon matrix was discovered in both mixtures. With a higher concentration of CH 4, it appeared at lower doses and was more pronounced. Two types of self-oscillations were observed long-period bursts (on a time scale of about 25 min) and short-period oscillations (of about 10 s). In pure solid Ar delayed desorption was not observed despite the accumulation of a significant number of excess electrons, exceeding their number in mixtures of Ar and CH 4 as it was found by measurements of thermally stimulated exoelectron emission. This finding discards the model of Coulomb explosion for the phenomenon detected. We focused on the role of hydrogen in delayed desorption. The formation of atomic hydrogen in the matrix was traced via cathodoluminescence by the emission band of the excimer Ar 2 H * at 166 nm. Desorption of excited hydrogen atoms in the excited state was detected by the Ly- α emission line. A decrease of the Ar 2 H * band intensity at higher concentration of CH 4 was found evidencing bleaching these centers likely due to recombination of H atoms with energy release and formation of molecular hydrogen. The data obtained give additional evidence in favor of the hypothesis that the exothermic reactions of radiolysis products serve as a stimulating factor for delayed desorption. [1] R.E. Johnson, R.W. Carlson, T.A. Cassidi and M. Fama, 2013 in The Science of Solar System Ices, eds. M.S. Gudipati and J. Castillo-Rogez, 356 (New York, Springer) 551. [2] J. M. Carpenter, Nature 330 (1987) 358. [3] E. Kulagin, S. Kulikov, V. Melikhov and E. Shabalin, NIM B 215 (2004)

96 94 Quantum liquids and quantum crystals, cryocrystals CONCENTRATION AND MOLAR VOLUME DEPENDENCE OF THERMAL CONDUCTIVITY OF RARE GAS SOLIDS SOLUTIONS A.V. Karachevtseva, V.A.Konstantinov, V.V. Sagan, V.P. Revyakin B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine Rare gas solids (RGS) Ar, Kr and Xe are the simplest substances whose atoms are connected by a weak van der Waals interaction and interatomic potential can be relatively easily modeled. A large number of experimental and theoretical studies have been devoted to examination of their thermal conductivity. Despite the abundance of information, it can be argued that the dependence of the isochoric thermal conductivity of Ar, Kr and Xe on temperature and molar volume has not been strictly established by experiment. It was only possible to affirm that the isochoric thermal conductivity is described with good accuracy by the expression κ=a/t n +B, where n varies between 1 and 2 with the appropriate choice of coefficients A and B [1]. Point defects cause additional scattering of phonons and, consequently, a decrease in thermal conductivity. The isochoric thermal conductivity of solid Kr with CH 4 and Xe admixtures was studied in the temperature range T D in [2,3]. It was found that as the impurity concentration increases, the phonon contribution to thermal conductivity decreases, and the thermal conductivity itself approaches its lower limit as it was interpreted by Cahill, Watson and Pohl [4]. In this study the isochoric thermal conductivity of Kr 0.63 Xe 0.37 solid solution has been investigated for three samples with different molar volumes in the temperature range from 80 K to the onset of melting, as well as the thermal conductivity of the ternary (Kr 0.63 Ar Xe ) and quaternary (Kr 0.63, Ar 0.12 Xe 0.12 (CH 4 ) 0.13 ) solid solutions. The thermal conductivities of double, triple and quaternary solid solutions are close to each other and to the calculated lower limit of thermal conductivity κ min. It is shown that coefficient A responsible for the phonon contribution depends essentially on the density (molar volume) and the impurity concentration (see Fig.1), while the coefficient B describing the diffuse contribution is practically constant. The Bridgman coefficient g ln / lnv T decreases from g 9 10, characteristic for pure Kr, to g 3 4 with an increase in the concentration of Xe and CH 4 impurities above 10%. Fig.1. Isochoric thermal conductivity of Kr with Xe admixture represented in coordinates κt(t). [1] V.A. Konstantinov, V.V. Sagan, A.V. Karachevtseva, LTP, 44, 840 (2018). [2] V.A. Konstantinov, V.G. Manzhelii, V.P. Revyakin, R.O. Pohl, LTP, 27, 858 (2001). [3] V.A. Konstantinov, V.P. Revyakin, R.O. Pohl, Phys. Solid State, 44, 857 (2002). [4] D.G. Cahill, S.K. Watson, R.O. Pohl, Phys. Rev. B., 46, 6131 (1992).

97 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine STRUCTURE DETERMINATION OF LOW-TEMPERATURE PHASE OF SOLID MONOSILANE SiH 4 USING LENNARD-JONES POTENTIALS. CALCULATION D.E. Hurova 1,2, N.N. Galtsov 2, A.I. Prokhvatilov 2 1 V.N.Karazin KharkivNatsonal University, 4 Svobody Sq., Kharkiv, 61022, Ukraine 2 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine 47 Nauky Ave., Kharkiv, 61103, Ukraine dianagurova37@gmail.com SiH 4 is a molecular substance and belongs to the group of methanes. Molecular crystals have this property: the intermolecular forces are much weaker then the intramolecular ones. A feature of molecular crystals is the presence of an order-disorder phase transition. It was found that SiH 4 in the solid state has one phase transition with temperature Tc = K. It was shown that both phases of monosilane have a monoclinic structure with Z = 4 molecules in the ordered phase, and Z = 32 molecules in the disordered phase [1]. SiH 4 structures at high pressures and Lennard-Jones potentials has been determined [2]. When we know the lattice type, Lennard-Jones parameters, the amount of interaction of SiH 4 molecules with each other, we determine the position and mutual orientation of the molecules in the lowtemperature phase, minimizing the lattice interaction energy. The resulting structure with the minimum lattice interaction energy will completely describe our molecule and we can talk about the most probable symmetry group for the low-temperature SiH 4 phase. [1] A.I. Prokhvatilov, N.N.Galtsov, N.A.Klimenko and M.A.Strzhemechny, LTP, 34, 142 (2008). [2] Yuk. Sakiyama, Shu Tacardi, Y. Matsumoto, J. Chem.Phys. 122, (2005). 95

98 96 Quantum liquids and quantum crystals, cryocrystals NONLINEAR BEHAVIOR OF THE QUARTZ TUNING FORK IN VACUUM AND He II Kh. Mykhailenko 1, T. Dubchak 2, G. Sheshin 1 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 V.N.Karazin Kharkiv National University, Svobody Sq. 4, Kharkiv,61022, Ukraine klokol@ilt.kharkov.ua Experimental studies of the properties of an oscillating quartz tuning fork immersed in superfluid helium in a wide temperature range have been carried out. It is shown that the nonlinear oscillations of the tuning fork in He II are well described by the nonlinear Duffing equation and are determined by the turbulent behavior of the surrounding superfluid liquid, in which the mutual friction force is proportional to the cube of the oscillation speed of the tuning fork prongs. Using the Duffing equation, the nonlinearity coefficient is determined at the critical point at which the turbulent flow is generated and the relationship between the nonlinearity coefficient and the mutual friction coefficient is found. The temperature dependence of the mutual friction coefficient was determined and it was shown that in the temperature range 0,55 K 0,25 K there is good agreement between the experimental data and the existing theoretical concepts.

99 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine EFFECT OF 3 He IMPURITY ON DAMPING OF TUNING FORK OSCILLATIONS IN SUPERFLUID HELIUM 97 V.A. Vrakina 1, S.S. Kapuza 1, V.K. Chagovets 1,2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 V.N. Karazin Kharkiv National University, Svobody Sq. 4, 61022, Kharkiv, Ukraine verikvrakina@rambler.ru At present, the problems of attenuation of resonators placed in a superfluid liquid remain little studied. It was previously established that in superfluid 4 He in a laminar flow regime, the main dissipation mechanism of an oscillating body is viscous friction at temperatures above ~ 0.6 K, whose contribution is well described by hydrodynamic equations. With decreasing temperature, the free path of thermal excitations of superfluid helium begins to exceed the characteristic dimensions of the tuning fork, the ballistic regime of dispersion of quasiparticles begins and the acoustic emission of the tuning fork (the first and second sounds) makes the main contribution to dissipation. The addition of 3 He impurity changes not only the temperature of the 4 He superfluid transition, but also both sound modes and the relationship between them. Since 3 He in solutions of 3 He 4 He is in the normal state, it contributes to the normal component of the flow and gives a different interpretation of the second sound - a wave of concentration 3 He appears. Therewith, the addition of 3 He leads to the fact that the hydrodynamic regime in solutions occurs in almost the entire temperature range and the contribution of the second sound increases. This paper presents the results of experimental studies of the damping mechanisms of tuning fork oscillations in pure 4 He and solutions of 3 He 4 He containing 5% and 15% 3 He, in the temperature range K. The experiments were carried out in opened and closed tuning forks, which made it possible to separate the attenuation contributions due to viscous forces and the radiation of the first and second sounds. It was found that the temperature dependence of the damping of a oscillating tuning fork in 4 He and it is well described by the viscosity contribution in the entire hydrodynamic range, and at lower temperatures, by the contribution of the first sound radiation. In solutions of 3 He 4 He, the contribution of viscous friction well describes the temperature dependence of the attenuation of the tuning fork only above ~ 1.5 K. At lower temperatures, there is a significant discrepancy between experimental data and theory, which cannot be explained by the contributions of radiation from the first and second sounds. The reasons for this discrepancy are discussed.

100 98 Quantum liquids and quantum crystals, cryocrystals NMR MULTIECHO IN 3 He ADSORBED BY THE NANOSTRUCTURED SiO 2 MATERIAL MSM-41 А.P. Birchenko 1, Ya.Yu. Fysun 1, N.P. Mikhin 1, A.S. Taran 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv 61103, Ukraine 2 V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, 61022, Ukraine alinataran1296@gmail.com, mikhin@ilt.kharkov.ua Previously, multi-echo was observed in NMR studies of liquid and solid 3He [1-3] and solutions of 3He-4He [4, 5]. The origin of multi-echo in these works is associated with nonlinear effects in the dynamics of magnetization at large gradients of the magnetic field. After of the usual ( normal ) spin echo at time points (n + 1) τ (here n = 2, 3,...), a series of responses of a system of nuclei at the resonant frequency (multi-echoes) amplitude of which was significantly less than the usual echo, appeared. Now, such technique was used for the alternative measurement of the spin diffusion coefficient Ds of 3He adsorbed. It was shown that in addition to the first 1.5 solid-like monolayers of 3He (coefficient Ds ~10-8 cm2 /s), the nano-tubes contain two additional 3He phases with D2~10-4 cm2 /s and D3~10-2 cm2/s. The measured values of D2 and D3 are in order of magnitude close to the values of spin-diffusion in liquid and gaseous 3He. Comparisons of results obtained by the traditional spin-echo method and by multi-echo method are carried out. [1] G. Eska, H.G. Willers, B. Amend, and W. Widemann, Physica B 108, 1155 (1981). [2] D. Einzel, G. Eska, Y. Hirayoshi, T. Kopp, and P. Wölfle, Phys. Rev. Lett. 53, 2312 (1984) [3] G. Deville, M. Bernier, and J.M. Delrieux, Phys. Rev. B 19, 5666 (1979). [4] G. Nunes Jr., C. Jin, A.M. Putman, and D.M. Lee, Physica B 169, 547 (1991). [5] N. Mikhin, V. Maidanov, LTP 31, 473 (2005).

101 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine LIOUVILLE EQUATION FOR A WEAKLY EXCITED LOW- TEMPERATURE GAS IN A RANDOM ELECTROMAGNETIC FIELD 99 Ye.V. Yedelkina 1, Yu.V. Slyusarenko 1,2 1 Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, Ukraine 2 Akhiezer Institute for Theoretical Physics,NSC KIPT,1 Akademichna Str., Kharkiv, Ukraine yelyzaveta.yedelkina@gmail.com We present an approach to derivation of the Liouville equation for a weakly excited lowtemperature gas, which is subjected to an external random electromagnetic field. The impact of an external stochastic field implies averaging of the statistical operator of the system over the probability density of the Gaussian process. To implement the averaging procedure, the Furutsu- Novikov formula is generalized to the system under study. A closed-form evolution equation is obtained for the averaged statistical operator, which should be considered as the initial one when constructing the kinetic theory of the considered system. The problem solved in this work represents the first stage in the description of the lowtemperature gas as a physical model of dissipative media with active fluctuations. [1] Yurii V. Slyusarenko, and Oleksii Yu. Sliusarenko, J. of Math. Physics 58, (2017). [2] А.G. Zagorodny, Yu.V. Slyusarenko, and S.N. Shulga, LTP 44, 1049 (2018).

102 100 Quantum liquids and quantum crystals, cryocrystals EXPERIMENTAL SETUP FOR STUDY OF SOLID HELIUM FLOW THROUGH A NARROW CAPILLARY D.S. Sedykh, S.P. Rubets, A.S. Neoneta, O.S. Rybalko, V.A. Maidanov B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine lososogar@gmail.com The design of the experimental device for the study of pulsed flow of solid helium in vacuum at low temperatures is developed. Previously, such experiments were carried out at high temperature above ~ 1.6 K [1 3], and the unusual behavior of solid helium pressure was found, which may be attributed to the formation of excessive non-equilibrium vacancies in the crystal. As was shown, the concentration of such vacancies should increase with decreasing temperature. The proposed construction will make it possible to carry out such experiments at temperature down to millikelvin range and to study a possibility of Bose-Einstein condensation of vacancies at their high concentration. [1] G. Benedek, F. Dalfovo, R. E. Grisenti, M. Kasz,x and J. P. Toennies, PRL 95, (2005). [2] G. Benedek, P. Nieto, and J. P. Toennies, Eur. Phys. J. B. 76, 237 (2010). [3] G. Benedek, A. Kalinin, P. Nieto, J. P. Toennies, Phys. Rev. B 93, (2016).

103 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 101 NANOPHYSICS AND Nanophysics NANOTECHNOLOGIES and Nanotechnologies

104

105 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine THERMAL TRANSPORT IN MOLECULAR DISORDERED CRYSTALS WITH LONG RANGE ORDER D. Szewczyk Institute of Low Temperature and Structure Research, PAS 2 Okólna Str., , Wrocław, Poland d.szewczyk@intibs.pl The nature of the amorphous state is recognized as one of the greatest challenges of condensed matter physics in the XXI century. In the quest for simple systems exhibiting glassy behaviors which may at least partially be applied as models, some disordered molecular crystals know as plastic crystals, seem to meet the requirements. The focus of the talk is on studies of singularities in thermal transport. For that reason as an introduction the different experimental methods of determining the thermal conductivity coefficient κ(t) and the heat capacity C p (T) will be presented. The main part will be devoted to elucidating the particular processes and mechanisms governing the heat transport of materials for which their molecules can retain a translational order being orientationally disordered between them upon cooling. The case studied are the derivatives of nitrobenzene crystal (C 6 H 5 NO 2 ), namely the orientationally disordered pentachloronitrobenzene and two phases of parachloronitrobenzene orientationally ordered and a disordered one. Although most of the results of κ(t) may be assign to the typical dependences expected in crystalline and amorphous states, some anomalous behavior are observed. The detailed analysis of the experimental data concerning the peculiarities, especially in the high temperature range, will be presented. Additionally the conclusions will be supported with heat capacity results. 103

106 104 Nanophysics and nanotechnologies STRUCTURAL FEATURES OF POINT-CONTACT SENSORS BASED ON TETRACYANOQUINODIMETHANE COMPOUNDS D.O. Harbuz 1,2, A.P. Konotop 2, V.A. Gudimenko 2, А.P. Pospelov 1, G.V. Kamarchuk 1 1 National Technical University Kharkiv Polytechnic Institute 2 Kyrpychov Str., Kharkiv, 61002, Ukraine 2 B. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine 47 Nauky Ave., Kharkiv, 61103, Ukraine zeyxes@gmail.com Over the past few years, on the basis of Yanson point contacts, which are the main instrument of Yanson point contact spectroscopy [1] and are actively used to determine the electron-phonon interaction function in metals, a number of new specific effects have been discovered, among which a point-contact gas-sensitive effect takes a special place [2]. This effect has shown broad prospects for the use of point contacts, including their utilization as sensors for such complex environment as human exhaled gas. It is well known that breath gas consists of more than 600 different volatile organic compounds, some of which are specific markers of various metabolic states of the human body. Our previous studies in this area showed the promising ability of TCNQ compounds-based point-contact sensors to be used for diagnosing various gastrointestinal diseases associated with Helicobacter pylori infection [3] and as devices which are sensitive to human emotional states [4]. This recently discovered ability provides the using of such sensors as a kind of polygraphs. The wide possibilities and unique results demonstrated by point-contact matrices based on TCNQ compounds determine the relevance of the study of their physical properties. In this work, the main emphasis was made on determining the characteristics of the morphology and structure of these sensitive elements. Point-contact matrices were obtained by combined physical-chemical deposition of TCNQ salt from its saturated solution in acetonitrile on substrates of textolite, which is foiled by copper, or on silicon substrates with a preliminarily thermally deposited 300 nm copper film. To analyze the obtained structures, the methods of scanning electron microscopy and X-ray diffraction in K α radiation of copper were applied. Results about the phase composition of the test objects were obtained, in particular, the presence of the metastable phase I of the Cu-TCNQ compound was revealed. Microscopic studies have shown a unique structure of the objects under study. This structure forms a mesoscopic matrix from a variety of Yanson point contacts, which acts as a sensitive element of the sensor. Thus, the research results make a fundamental contribution to the understanding the functioning features of point-contact gas sensors based on TCNQ compounds. The results obtained are also of great practical value, allowing us to concentrate our efforts on receiving sensors with precisely defined structural features, which in turn brings us closer to the possibility of implementing such devices into widespread using. [1] Yu.G. Naidyuk, I.K. Yanson. Point-contact spectroscopy (Springer, New York, 2005). [2] G.V. Kamarchuk, O.P. Pospelov, A.V. Yeremenko, E. Faulques, I.K. Yanson, Europhys. Lett., 76(4), 575 (2006). [3] I.Kushch, N.Korenev, L.Kamarchuk, A.Pospelov, A.Kravchenko, L.Bajenov, M.Kabulov, A.Amann, and G.Kamarchuk, J. Breath Res. 9(4), (2015). [4] G.Kamarchuk, A.Pospelov, A.Savytskyi, V.Gudimenko, V.Vakula, A.Herus, D.Harbuz, L.Kamarchuk, M.Pereira. To be published in the NATO Science Series (2019).

107 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine NOVEL PHENOMENA IN TWO-DIMENSIONAL MATERIALS: ELECTRICAL CONTROL OF INTERLAYER EXCITON DYNAMICS AND SIGNATURES OF SUPERCONDUCTIVITY IN ATOMICALLY THIN TWISTED HETEROSTRUCTURES K. Pistunova Department of Physics, Stanford University, Stanford, California 94305, USA The concept of reduced dimensionality in physical systems has long been studied as a purely abstract although mathematically interesting idea. However, the success of graphene has proven it possible to realize 2D systems experimentally and has led to the emergence of a whole family of crystalline 2D materials, among them an insulator boron nitride (BN) and transition metal dichalcogenides (TMDs). Although TMDs have been known for decades as inorganic semiconductors, the ability to isolate their single layers opened up new opportunities in nanoelectronics, optoelectronics and photonics. Moreover, the ability to stack TMDs in arbitrary configuration and with arbitrary twist angles shows great promise for the study of novel physical phenomena such as strongly correlated electron physics and superconductivity in purely twodimensional systems. In this talk I will describe our recent efforts of manipulating exciton quasiparticles in TMD heterostructures as well as quantum transport and emergence of superconductivity in small angle twisted TMD homobilayers. Excitons in semiconductors, bound pairs of excited electrons and holes, can form the basis for new classes of quantum optoelectronic devices. A van der Waals heterostructure built from atomically thin semiconducting transition metal dichalcogenides (TMDs) enables the formation of excitons from electrons and holes in distinct layers, producing interlayer excitons with large binding energy and a long lifetime. Employing heterostructures of monolayer TMDs, we realize optical and electrical generation of long-lived neutral and charged interlayer excitons. We demonstrate the transport of neutral interlayer excitons across the whole sample that can be controlled by excitation power and gate electrodes. We also realize the drift motion of charged interlayer excitons using Ohmic-contacted devices. The electrical generation and control of excitons provides a new route for realizing quantum manipulation of bosonic composite particles with complete electrical tunability. Moreover, the tight binding and small exciton Bohr radius potentially allows for quantum degeneracy of the composite bosons, which may lead to exciton condensation at significantly elevated temperatures compared to, e.g., conventional BECs of cold atoms. One other unprecedented feature of 2D materials is their insensitivity to the lattice mismatch between the layers, which allows a unique degree of freedom the twist angle between the layers and the moiré pattern that forms. It was previously shown that if two graphene layers are put precisely at a magic angle of 1.1 degrees, the band structure is modified so that the bands are completely flat, which leads to enhanced single particle density of states, Mott insulator regime at the half-filled moiré flat band and superconducting domes, not unlike that shown for high-t c superconductor. Remarkably, small twist angle TMDs homobilayers show flat bands for a much wider range of angles since their initial single layer parabolic band structure is already much flatter than that of graphene, making TMD more versatile for the study of strongly correlated electron physics and twist angle superconductivity. We demonstrate superconductivity in small twist angle TMDs homobilayers, exhibiting a zero-resistance state at low temperatures below 1 K with critical magnetic field of about 0.1T. The understanding of this novel superconducting state could not only expand our knowledge of highly correlated electron physics in 2D, but also pave the way to twistronics, a unique emergent field that relies on twist between 2D layers. 105

108 106 Nanophysics and nanotechnologies HIGHLY SELECTIVE NANODEVICES BASED ON CONDUCTANCE QUANTIZATION OF DENDRITIC POINT CONTACTS IN GASES AND LIQUID MEDIA A.O. Herus.1, A.V. Savytskyi 1, А.P. Pospelov 2, Yu.S. Doronin 1, V.L. Vakula 1, G.V. Kamarchuk 1 1 B. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 Department of Physical Chemistry, National Technical University Kharkiv Polytechnic Institute, 21 Kyrpychov Str., Kharkiv, 61002, Ukraine gerus@ilt.kharkov.ua Nanodevices have become part of our lives. They are widely used to solve a lot of problems in various fields. One of the typical examples of their successful application is utilization of modern nanosensors for detection of various gases. Gas media control is of great importance for both reliable operation of numerous technological cycles and protection of the environment. Despite the high level of modern sensing technologies, we often hear about accidents at factories caused by gas leaks not detectable with the human senses or by the existing devices. These gases can be lethal even in small concentrations. Therefore there is an urgent need to create instruments for detecting minute concentrations of hazardous gaseous substances. This can be achieved by employing new advanced approaches and principles in the sensor development. We propose a new concept of selective detection of gases and liquids based on the formation of an original quantum system and registration of its energy states in dynamic mode using Yanson point contacts of dendrites synthesized electrochemically in the medium under study [1]. The in situ synthesis of nanoscale dendritic point contacts is part of the cyclic switching effect [2] which takes place in the electrolyte in contact with the analyzed medium and consists of alternating cycles of formation and destruction of point contacts. Conductance of such point contacts exhibits a quantum behaviour related to the shell effect which shapes the process of formation of dendritic point contacts and determines the geometry of their conduction channels. As a result, the dependence of resistance R(t) contains sections of constant conductance (steps) corresponding to the metastable states of point contacts. The conductance steps are used to derive conductance histograms of the synthesized point contacts, which display the distribution of their metastable energy states. Histograms obtained in different gas environments are found to be fundamentally different. This allows high-precision detection of various gas media. The obtained results can become a basis for the development of a new quantum technology of selective detection of various gaseous agents. [1] G.V. Kamarchuk, A.P. Pospelov, A.V. Savytskyi, A.O. Herus, Y.S. Doronin, V.L. Vakula, E. Faulques, Springer Nature Applied Sciences, (3): 244 (7). [2] A.P. Pospelov, A.I. Pilipenko, G.V. Kamarchuk, V.V. Fisun, I.K. Yanson, and E. Faulques, J. Phys. Chem. C, (1): p

109 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine ELECTRICAL RELAXATION PROCESSES AND THEIR PHASE PORTRAITS IN NANOSYSTEMS 107 D.A. Dolhopolova 1, V.A. Lykah 2, E.S. Syrkin 3 1 V. N. Karazin Kharkiv National University 4 Svobody Sq., Kharkiv, 61022, Ukraine 2 National Technical University "Kharkiv Polytechnic Institute" 2 Kirpichov Str., Kharkiv, 61002, Ukraine 3 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine 47 Nauky Ave., Kharkiv, 61103, Ukraine d.a.dolgopolova@gmail.com Relaxation processes occur in systems in which, besides an effective resistance R, a reactance (such as a capacity C, for example) also exists. A presence of the reactance causes current to appear (disappear) not immediately, but exponentially within the specific relaxation time τ=rc [1]. The occurrence of the relaxation processes gives rise to self-oscillations which occur only in nonlinear systems. Nowadays the research of characteristics of relaxation processes becomes especially interesting in nanosystems due to using in sensor devices [2]. In present work the relaxation oscillations are considered on the example of a neon lamp circuit, and also oscillation phase portraits were built. Suppose, for the simplicity, that the capacitor discharging time is quite small compared to the charging time. Therefore, the oscillation period is the time during which the voltage rises from U2 (the extinction voltage) to U1 (the firing (breakdown) voltage): Here E is the supply voltage. Condition of relaxation oscillations occurrence is the following [1]: Here I 2 is the extinction current of the lamp, R cr is the critical value of resistance. After the first firing or extinction of the neon lamp a periodic process will be established in the circuit. The oscillations will consist out of two alternating process: the capacitor charging through the resistance with unlit lamp and the capacitor discharging through the glowing lamp. It is convenient to analyze the emerged oscillation process via phase portraits. (1) (2) Fig.1. The phase portrait of the neon lamp circuit in the case of (2). Here q e is the lamp charge when the voltage equals to U 2 (the extinction voltage); q f is the lamp charge when the voltage equals to U 1 (the firing (breakdown) voltage). On the Fig.1. the straight line is corresponded to VA - characteristics of the capacitor (linear dependence), the S-shaped curve to VA-characteristics of the neon lamp (nonlinear dependence) and the phase portrait is shown by the arrows. [1] A.A. Andronov, A.A. Vitt, S.E. Khaikin, Theory of Oscillators (Dover Publications, NY, 2011). [2] A.P. Pospelov, A.I. Pilipenko, G.V. Kamarchuk, V.V. Fisun, I.K. Yanson, E. Faulques, J. Phys. Chem. C, (1): p

110 108 Nanophysics and nanotechnologies CALORIMETRIC STUDIES OF MWCNTs M.S. Barabashko 1, D. Szewczyk 2, M.I. Bagatskii 1, V.V. Sumarokov 1, A. Jeżowski 2, V.L. Kuznetsov 3,4, S.I. Moseenkov 3, A.N. Ponomarev 5 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, , Wroclaw, Poland 3 Boreskov Institute of Catalysis, 5 Lavrentiev Ave., , Novosibirsk, Russia 4 National Research Tomsk Polytechnic University, 30 Lenin Ave., , Tomsk, Russia 5 Institute of Strength Physics and Materials Science of SB RAS 2/4 Academicheskii Ave., , Tomsk, Russia barabasсhko@ilt.kharkov.ua The specific heat of multi-walled carbon nanotubes (MWCNTs) has been studied in the temperature range from 1.8 to 275 K on the PPMS by the thermal relaxation method. The initial MWCNTs with a controlled level of defects and low content of inorganic impurities were obtained by CVD. All MWCNTs powders were washed from the catalyst. Two types of MWCNTs prepared by various technological procedures were investigated: 1) the initial powder was milled; 2) the initial powder was milled and oxidized. The transmission electron microscopy (TEM), Raman spectroscopy, X-Ray Fluorescence method (XRF), the energy dispersive X-ray spectroscopy (EDS) were used for the determination of the elemental composition and morphology of MWCNTs [1,2]. MWCNTs in the sets have an average diameter of 7 nm and 18 nm. It was found that the temperature dependence of the specific heat of the studied MWCNTs significantly differs from the specific heat of other carbon materials at low temperatures, as well as in the case of the initial powders. The specific heat capacity of MWCNTs significantly depends of the diameter of the nanotubes at low temperatures. The ratio of the heat capacity of nanotubes with diameters of 7 nm and 18 nm is about 3 at 2 K [3]. The observed effects of influence of grinding and oxidation on the behavior of the temperature dependence of the heat capacity of MWCNTs are qualitatively different for nanotubes with different diameters. The discussed features of the temperature dependence of the specific heat capacity of MWCNTs are, apparently, the manifestation of the size effect. [1] V.L. Kuznetsov, S.N. Bokova-Sirosh, S.I. Moseenkov, A.V. Ishchenko, D.V. Krasnikov, M.A. Kazakova, E.D. Obraztsova, Phys. Stat. Sol. (b), 251(12), 2444 (2014). [2] S.N. Bokova-Sirosh, V.L. Kuznetsov, A.I. Romanenko, M.A. Kazakova, D.V. Krasnikov, E.N. Tkachev, Y.I. Yuzyuk, E.D. Obraztsova, J. Nanophotonics, 10(1), (2016). [3] V.V. Sumarokov, A Jeżowski, D Szewczyk, M.I. Bagatski, M.S. Barabashko, A.N. Ponomarev, V.L. Kuznetsov, S.I. Moseenkov, Low Temp. Phys. 45, 347, (2019).

111 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine EFFECT OF COLD PLASMA TREATMENT ON HYDROGEN SORPTION BY GRAPHENE OXIDE R.M. Basnukaeva 1, A.V. Dolbin 1, V.B. Eselson 1, V.G. Gavrilko 1, N.A. Vinnikov 1, M.V. Khlistuck 1, S. Cherednychenko 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, Prospekt Nauky, 47, Kharkiv 61103, Ukraine 2 National Technical University «Kharkiv Polytechnic Institute» 2, Kyrpychova str.,61002, Kharkiv,Ukraine basnukaeva@ilt.kharkov.ua Plasma surface treatment has been successfully used for many years to change the structure and chemical composition of the near-surface layer of atoms in order to improve the bonding characteristics and obtain new physical properties of materials. Plasma technology became particularly useful following the development and wide spread application of nanostructures formed in a monolayer or a frame, whose entire volume is affected by plasma treatment. Such treatment seems very promising for materials formed by new allotropic modifications of carbon, i.e. modifications by fullerenes, nanotubes, and graphene. Using thermo-programmed desorption and X-ray diffraction, the present study investigated the effect of treatment with pulsed high-frequency discharge in a hydrogen environment on the structure and sorption characteristics of the thermal reduced graphene oxide (TRGO). Treatment TRGO by a pulsed gas discharge led to chemisorption of hydrogen, as well as greater physical sorption of hydrogen. We can assume this increase in sorption capacity is due to changes in the equivalent pore sizes that result from chemical interaction of the carbon atoms of TRGO layers with hydrogen ionized during the discharge process. 109

112 110 Nanophysics and nanotechnologies THE INFLUENCE OF ION EXCHANGE WITH SILVER IONS TO PHYSICAL PROPERTIES OF CADMIUM SULFIDE NANOPARTICLES L.R.Gahramanli 1, M.B.Muradov 1, Á.Kukovecz 2, O.O. Balayeva 3, G.M. Eyvazova 1, Z.M. Mukhamedova 1 1 Department of Physics, Baku State University, Z. Khalilov str., 23, AZ-1148 Baku, Azerbaijan 2 Departments of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary 3 Department of Chemistry, Baku State University, Z.Khalilov str., 23, AZ-1148 Baku,Azerbaijan qahramanli.lala@mail.ru In nanoparticles preparation, it is very important to control the particle size, particle shape and morphology[1]. CdS is one of the interesting materials of II-VI group s semiconductors. The prominent application fields of CdS is nonlinear optical devices, flat panel displays, light emitting diodes, lasers, logic gates, transistors, etc.[2-4]. CdS nanoparticles were synthesized by sonochemical method for 2 hours. After obtaining pure CdS powder, for ion exchange process of CdS nanoparticles with silver ions was selected two different concentration of solution: 0,005M and 0,1M. The selected two - low and upper concentrations were studied with Uv-vis at different times. The peaks with 2θ values of 25.87, 43.10, for pure CdS nanoparticles correspond to the (110), (220), (311) planes of the cubic phase CdS and compatible to (JCPDS Card No ) card. The XRD result of 0,005M solution of ion exchange, compatible to result of pure CdS nanoparticles. The XRD pattern of the 0,1M solution of ion exchange, containing silver sulfide nanoparticles and may be assigned to the (110), (-113), (-122), (013), (031), (-202), (014), (224) Miller indices. The formed particles are compatible to the monoclinic silver sulfide Ag2S from literature review [5]. The crystal structure of the samples has changed from the cubic phase of cadmium sulfid to monoclinic silver sulphide with increasing Ag+ ions concentrations. Band gap were determined 2.25 ev, 1.62 ev and 1.60 ev according to CdS, 0,005M and 0,1M of solution of ion exchange. In Table.1 is given the value of the band gap zone of nanoparticles measured in different times. However, band gap zone is divided into two parts. This is show that, in the sample are formed two structures: CdS and Ag2S. The results show that the value of the band gap is increasing by time. Table1. Band gap value of nanoparticles after ion exchange in different time intervals. Samples 15 min 45 min 75 min 0.1M solution of Ag + ions 1.2 ev ; 1.65eV 1.4 ev; 1.9 ev 1.4 ev; 2 ev 0.005M solution of Ag + ions 1.7 ev; 2.45 ev 1.7 ev; 2.52 ev 2 ev; 2.8 ev Increasing of concentration of solution in ion exchange process, has led to the transformation of the cation source. It shows itself in XRD and UV results. The UV results from measured at different times show the formation of two phases. [1] Alagar.M. et al./int. J. Phy. Sci., 2011, v.6, p [2] Pan H. et al. / J. Phys. Chem. C, 2008, v.112, p [3] Lin Y.F. et al. / Adv. Mater., 2008, v. 20, p [4] Shen G.Z. et al. /J Phys. Chem. B., 2005, v. 109, p [5] A. I. Gusev et al. / Semiconductors, 2016, Vol. 50, No. 5, pp

113 n, mol/g X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine HYDROGEN SORPTION IN HYBRID NANOSTRUCTURED CARBON/PALLADIUM MATERIALS AT LOW TEMPERATURES 111 D.O. Gritsay 1, R.M. Basnukaeva 2, A.V. Dolbin 2, V.B. Eselson 2, V.G. Gavrilko 2, N.A. Vinnikov 2, M.V. Khlistuck 2, V.I. Dubinko 3 1 National Technical University «Kharkiv Polytechnic Institute» 2, Kyrpychova str.,61002, Kharkiv,Ukraine 2 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine 47 Nauky Ave., Kharkiv, 61103, Ukraine 3 National Science Center Kharkov Institute of Physics and Technology" 1, Akademicheskaya St., Kharkiv, 61108, Ukraine basnukaeva@ilt.kharkov.ua Palladium is one of the strategic metals that determine the development of the economics. Using of palladium outperforms all other metals of the platinum group by quantity of application. The main consumer of this raw material is the automomobile industry. In this area, almost all palladium is used for producing catalysts. Considering the high cost of palladium, it is advisable to reduce its amount as much as possible simultaneously by increasing the active surface by creating a composite material containing nano-size palladium clusters. Microporous coal for a carbonate matrix, which contains palladium clusters, was obtained by carbonization and chemical activation from plant material. The value of the specific surface of the carbon matrix is in the range of m 2 /g. Sorption characteristics of a sample of porous carbon containing nanoclusters of palladium with respect to molecular hydrogen and deuterium has been investigated. The studies were observed in the temperature range K. The saturation of the sample with hydrogen isotopes was initiated at a temperature of 110 K and a pressure of 10 Torr. During the saturation and subsequent cooling of the sample, the pressure of the hydrogen gas in the measuring system was maintained times less than the equilibrium pressure of saturated vapor of H 2 or D 2 at a given temperature. Additional portions of gas were added to the cell during sorption. The temperature dependences of the amount of hydrogen and deuterium desorbed from the sample according to the method [1] are shown in Fig S H 2 D Fig.1. Temperature dependences of the relative amount of hydrogen (circles) and deuterium (triangles) desorbed from a sample of porous carbon containing palladium nanoclusters. Low-temperature features are marked with circles T, K Indicated in Fig 1. low-temperature features can explaining by changes in the structure and equivalent pore size of the sample when saturated with hydrogen isotopes and necessitate further research. [1] A.V. Dolbin, V.B. Esel'son, V.G. Gavrilko, V.G. Manzhelii, N.A. Vinnikov, S.N. Popov, B. Sundqvist, Low Temp. Phys. 34, 678 (2008).

114 112 Nanophysics and nanotechnologies DEPENDENCE OF TUNNEL RESISTANCE FOR POWDERS OF COMPACTED CHROMIUM DIOXIDE NANOPARTICLES ON THICKNESS AND TYPE OF DIELECTRIC SHELLS V.A. Horielyi, N.V. Dalakova, E.Yu. Beliayev B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine The influence of the properties of the dielectric barrier between ferromagnets, including the properties of the ferromagnet dielectric interfaces and the role of structural disorder in the barrier itself on the tunnel resistance and magnetoresistance is one of the important and insufficiently studied problems of tunnel ferromagnetic transitions. Within this problem, we investigated how the properties and the thicknesses of intergranular dielectric layers influence the magnitude of the tunnel resistance for pressed powders of ferromagnetic half-metal CrO 2. The thickness and properties of dielectric layers are largely determined by the technology used in the preparation of pressed powders. In our work, the synthesis of chromium dioxide was carried out by the use of hydrothermal method. General features of the technology used are described in [1]. The thickness of the dielectric interlayers was determined both directly (using a high resolution TEM) and indirectly, for example, by the consumption of reagents in the formation of dielectric layers or by studying the specific magnetization. For resistance measurements, we used samples consisting of CrO 2 nanoparticles covered by either chromium oxyhydroxide ( -CrOOH) or Cr 2 O 3. The measurement results are shown in Fig.1 and Fig.2. Temperature dependences (T) for CrO 2 samples with dielectric shells of particles made of identical material (Cr 2 O 3 ) with different thicknesses demonstrate a higher resistance for the sample with a thicker shell. This is due to the fact that electrons have to overcome a wider potential barrier between FM CrO 2 granules. On the other hand, the resistance of the samples consisting of nanoparticles covered by AFM dielectric shells of different types, but of approximately the same thickness, also significantly differ (Fig. 2). It should be noted that the sample with dielectric shell made of -CrOOH has a higher resistance. The latter may be connected both with the increase in the barrier height for this type of shell, and with larger distortions for the interfaces in the nanoparticle system CrO 2 -CrOOH, than in the nanoparticle system CrO 2 Cr 2 O 3. 1 M.G. Osmolovskiy, I.I. Kozhina, L.Y. Ivanova, O.L. Baydakova. J. Appl. Chem. v.74, p.3 (2001). Fig.1. Temperature dependences of resistance for two samples of CrO 2 half-metal nanoparticles covered by shells of dielectric Cr 2 O 3 with different thickness. Fig.2. Temperature dependence of resistance for two samples with dielectric shells of approximately the same thickness, but made of different materials: - - -CrOOH, - - Cr2O3.

115 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine REDOX ACTIVITY OF ORTHOVANADATE NPs DOPED WITH EUROPIUM IONS LnVO 4 :Eu 3+ (Ln = Gd, Y, La) 113 K.A. Hubenko, S. Yefimova, P. Maksimchuk, N. Kavok, V. Klochkov Institute for Scintillation Materials of NAS of Ukraine, 60 Nauky Ave., Kharkiv, 61072, Ukraine k.hubenko@gmail.com Reactive oxygen species (ROS) mainly including superoxide inions (O 2 - ), hydroxyl radicals ( OH), hydrogen peroxide (H 2 O 2 ) and singlet oxygen ( 1 O 2 ) are known to have edged sword properties in the determination on cell fate. ROS are continuously generated in small amounts in normal cells. Intracellular ROS levels is regulated via a cell antioxidant defense system (superoxide dismutase, catalase, glutathione peroxidases, peroxiredoxins and other enzymes and antioxidants) converting excess of ROS into less reactive species (O 2 or H 2 O, for instance) [1]. When the action of cell antioxidants become depleted, the level of ROS increases causing oxidative stress through the oxidation of lipids (lipid peroxidation), protein and DNA damage, etc. [2]. It is now generally accepted that the oxidative stress caused by imbalance on ROS production and scavenging is closely related to a broad spectrum of diseases including cancer [2] as well as aging [3]. So, control of the intracellular ROS level is critical for both normal and cancer cells. Recently, nanoparticles (NPs) have been proposed to fulfill this function. It has been shown that metal oxide nanoparticle possess pro- and antioxidant activities depending on their surface properties, size, concentration and redox potential [1, 4]. The brilliant example of antioxidant NPs (ROS scavenging agent) is cerium oxide NPs (nanoceria), which unique self-regenerative properties are the subject of numerous studies [5]. In this present study, we report switching the redox activity of orthovanade NPs doped with europium ions LnVO 4 :Eu 3+ (Ln = Gd, Y, La) driven by UV or X-ray irradiation Evaluation of the redox activity of LnVO 4 :Eu 3+ (Ln = Gd, Y, La) NPs was carried out using lipid oxidation measurement (conjugated dienes formation test), NPs redox-activity at UV- and X- ray irradiation. It has been shown that LnVO 4 :Eu 3+ NPs revealed both pro- and antioxidant activity (ROS generation or scavenging ability) depending on a type of irradiation or its absence. To the best of our knowledge, such phenomenon for Re orthovanadate NPs have been observed for the first time. [1] C.A. Ferreira, D. Ni, Z.T. Rosenkrans, and W. Cai. Nano Research. 11, 4955, (2018). [2] B. Hennig, C.K. Chow. Free Radic. Biol. Med. 4, , (1988). [3] K.B. Beckman, B.N. Ames. Physiol. Rev. 78, , (1998). [4] L. Ibaňez, C. Notcovich, P.N. Catalano, M.G. Bellino. Cancer Letter 359, 9-19, (2015). [5] Yu. Malyukin, V. Klochkov, P. Maksimchuk, V. Seminko, N. Spivak. Nanosc Res Lett. 12, 566, (2017).

116 114 Nanophysics and nanotechnologies DELTA-DOPED QUANTUM WELLS AND BACKGROUND IMPURITIES Ya. Kotov 1, R. Demediuk 1, V. Akimov 2, C.A. Duque 3, A. Tiutiunnyk 4, D. Laroze 4, D. Sushenko 1, V. Tulupenko 1 and O. Fomina 1 1 Donbass State Engineering Academy, Kramatorsk, Ukraine. 2 Facultad de Ciencias Básicas, Universidad de Medellín, Medellín, Colombia. 3 Grupo de Materia Condensada-UdeA, Universidad de Antioquia, Medellín, Colombia. 4 Instituto de Alta Investigación, CEDENNA, Universidad de Tarapacá, Arica, Chile. kotov @gmail.com We showed [1-3] that ionization of shallow impurities arranged as a delta layer within the quantum well (QW) with relatively small concentration increases their binding energy and changes the separation between couples of the first neighboring space-quantized energy levels. Here the term relatively small means that we treat impurities as isolated ones or in other words, impurity binding energy (IBE) does really exist. The reason for discussed phenomena is the fact that the charges of (partly) ionized delta layer together with free electrons in the QW create what is called the Hartree potential. This potential digs out its own electrostatic QW, which is superimposed on the original (presumably rectangular) energy profile created by heterostructure. To clear up all the peculiarities of this phenomenon we did not take the background impurities into attention earlier. Meanwhile they exist in any real heterostructure or they can be introduced by intentionally for example as a delta doping of barriers (a so-called, modulation doping). But independently of the way of doping of impurities in the barriers (uniform or as a delta layer), they supply additional electrons into the QW. It results in appearing the depletion layers in the barriers and of potential pockets in the QW near the heterointerfaces. All this change the energy profile of the QW even without delta layer within the QW. Thus the main goal of our work is to found out the way of influence of impurities in barriers (for definicity we take a uniform doping of the structure by residual impurities) on discovered by us phenomena. We present a big body of data, and trace the influence of different concentration of residual impurities on the discussed phenomenon for different depths of the QWs. [1] V. Tulupenko, A. Abramov, Ya. Belichenko, V. Akimov, T. Bogdanova, V. Poroshin, and O. Fomina. J. Appl. Phys. 109, (2011). [2] V. Tulupenko, C.A. Duque, R. Demedyuk, Ya Belichenko, C.M. Duque, V. Akimov, V. Poroshin, O. Fomina, Philos. Mag. Lett. 93 (2013) 42. [3] V.Tulupenko, C.A.Duque, R.Demediuk, V.Belykh, A.Tiutiunnyk, A.L. Morales, V. Akimov, R.L.Restrepo, M.E.Mora-Ramos, V.Poroshin, O.Fomina. Physica E, 66 (2015)

117 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine MAGNETORESISTANCE OF NANOGRAPHITE PARTICLES WITH DIFFERENT STRUCTURE 115 T. Len 1, I. Ovsiienko 1, O. Syvolozhskyi 1, O. Marinin 1, I. Mirzoiev 2, I. Berkutov 2,3, V. Andrievskii 2, D. Shpylka 1, L. Matzui 1 1 Taras Shevchenko National University of Kyiv, Departments of Physic 1 and Biophysics 4, Volodymyrska Str., 64/13, Kyiv, Ukraine 2 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 3 Department of Physics, North Carolina State University, Raleigh, NC 27695, USA talen148@gmail.com The work presents the results of investigations of resistivity in magnetic fields for nanographite particles with different structure. The specimens of nanographite particles were obtained with different methods: chemical treatment (1.5 М solution of KMnO4 in 20% H2SO4 on the sand bath) and ultra-sonic treatment in different chemical environments (water, ethanol, acetone) of source thermoexfoliated graphite (TEG). The structure of obtained nanographite specimens was investigated by electron microscopy and Raman spectroscopy methods. It is shown from structural investigations that the chemical treatment of source TEG lets to get the planar defective graphenelike sheets with small number of graphite. The lateral crystalline size for this nanographite does not exceed the 5 nm. The sonication of source TEG results in the formation of nanographites with a weekly expressed defects in graphite layers with lateral crystalline size ~ 40 nm. In detail nanographite obtaining methods and their structure are described in detail in [1]. The Figure 1 presents the typical dependences of resistivity in magnetic field ( / (B)) for bulk specimens of chemically treated (a) and sonicated (b) nanographites., % T = 293 K T = 77 K 0,0 0,3 0,6 0,9 1,2 B, T T = 77 K T = 293 K В, Т Fig. 1. Dependences / (B) for chemically treated (a) and sonicated (b) nanographites a) b) As it follows from Fig. 1 the magneto-resistance of chemically treated nanographite is quadratic and positive at room temperature. At T = 77K magnetoresistance of this specimen is negative. The negative magnetoresistance is explained in terms of charge carriers week localization effect. This effect is observed in disordered graphites and carbon nanotubes with unperfected structures. A completely different character of field dependence of magnetoresistance is revealed for sonicated nanographites. For these specimens magnetiresistance is positive and almost does not dependent from temperature. At magnetic field more than 1.2 T there is linear dependence of magnetoresistance from magnetic field. This effect is satisfactorily described in the terms of Abrikosov model of quantum linear magnetoresistance. Thus, magnetoresistance is very sensitive to the degree of structural perfection of nanographite particles. Minor changes in the degree of defects of nanographite lead to significant changes in the mechanisms of magnetoresistance. [1] I. Ovsiienko, Т. Len, L. Matzui, O. Lazarenko, F. Le Normand, A. Shames. Ukr. Jour. of Physics. 63, 759 (2018).

118 116 Nanophysics and nanotechnologies MOLECULAR PHOTODIODE AS A LIGHT EMITTER V.O. Leonov, E.G. Petrov, Ye.V. Shevchenko Bogolyubov Institute for Theoretical Physics of NAS of Ukraine, 14-b Metrolohichna str. Kiev, 03143, Ukraine leogluck@gmail.com The nonequilibrium density matrix approach was used to derive the kinetic equations describing the transmission of an electron in the molecular junctions electrode 1 molecule electrode 2 (1M2-system). Considering the steady-state transmission regime, we carried out the detailed analysis of the kinetics of electrofluorescence formation in systems with symmetric and asymmetric couplings between the molecule and the electrodes. It was shown that systems with an asymmetric couplings behave itself as diodes. For such systems, the possibility of electrofluorescence occurrence is shown. It was shown that the optically active state of the molecule is formed as a result of electron hops between the molecule and each of the electrodes, as well as due to inelastic interelectrode tunneling of the electron. It was shown that electrofluorescence power for a molecular diode depends on the polarity of the voltage bias applied to the electrodes. Considering optically active part of the molecule (chromophore group) in HOMO-LUMO approach, the polarity of electrofluorescence was explained. It was shown that two mechanisms of the emergence of polarity are revealed. One mechanism is associated with nonidentical Stark shifts of the HOMO and LUMO levels relative to the Fermi levels of the electrodes. The second mechanism is associated with the fact that the rates of an electron hopping between HOMO (LUMO) and one of the electrodes are much higher than the rates of such a hopping with the other electrode. The conditions in which each mechanism can be implemented experimentally were indicated. [1] E.G. Petrov, V.O. Leonov, Ye.V. Shevchenko. Bipolar and Unipolar Electrofluorescence in a Molecular Diode. JETP Letters, 2017, Vol. 105, No. 2, pp [2] E.G. Petrov, V.O. Leonov, Ye.V. Shevchenko. Electrofluorescence Polarity in a Molecular Diode, JETP, 2017, Vol. 125, No. 5, pp

119 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine PECULIARITIES OF PHONON EXTENSION IN GRAPHENE NANOSTRUCTURES 117 K.A. Minakova 1, I.A. Gospodarev 2, S.B. Feodosyev 2, E.S. Syrkin 2 1 National Technical University «Kharkiv Polytechnic Institute», 2 Kyrpychova str., Kharkiv, Ukraine 2 B. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave, Kharkiv 61103, Ukraine friday.marjory.johnes@gmail.com The interest in the phonon spectrum is because the band of its spectrum for graphite nanofilms is very wide. The estimated Debye temperature for graphite is about 2500 K, and, consequently, the phonon heat capacity increases with temperature much more slowly than that of other solids. At room temperature, it is still far from saturation. The electron contribution to the total heat capacity cannot be considered negligible compared to the phonon contribution. Therefore, analysis based on microscopic calculations of the temperature dependences of the heat capacity of graphite and carbon nanofilms is very necessary for the correct interpretation of calorimetric measurements. It should also be noted that the experimental study of low-temperature heat capacity is an important and reliable source of information on quasiparticle excitations and, in particular, on phonon spectra. Calorimetric experiments, as a rule, are very accurate and, unlike most optical and ultrasonic experiments, do not require high-quality single crystals. The weakness of the interlayer interaction in graphite leads to the fact that at frequencies higher than the frequency of the first van Hove singularity (which is approximately 2% of the bandwidth of its quasi-continuous phonon spectrum), it is quasi-two-dimensional character. For oscillations polarized in the layer plane in the long-wave limit, the dispersion law is linear (acoustic mode), and for oscillations polarized across the layer, the dispersion law in the long-wave limit tends to quadratic. In addition, these modes practically do not interact with vibrations polarized along the layer, that is, these vibrations are practically described by a two-dimensional scalar model on the honeycomb lattice, and their dispersion law will be similar to the dispersion law of the graphene electron spectrum. On the density of states of this phonon mode, there is a feature similar to the V-shaped (Dirac) feature on the density of electron states. Near this frequency (~ 15 THz), the phonon group velocity is high. The presence of these fast-spreading propagating high-frequency phonons should affect the electron-phonon interaction in graphene nanofilms and, under certain conditions, ensure the transition of graphene nanostructures to the superconducting state. [1] V.V. Eremenko, A.F. Sirenko, V.A. Sirenko, I.A. Gospodarev, E.S. Syrkin, S.B. Feodosyev, I.S. Bondar, K.A. Minakova, Low. Temp. Phys. 42, 401 (2016). [2] V.V. Eremenko, V.A. Sirenko, I.A. Gospodarev, E.S. Syrkin, S.B. Feodosyev, I.S. Bondar, K.A. Minakova, A Feher, Journal of Physics: Conference Series. 969, (2018). [3] I.A. Gospodarev, V.I. Grishaev, E.V. Manzhelii, E.S. Syrkin, S.B. Feodosyev, K.A. Minakova, Low. Temp. Phys. 43, 322(2017).

120 118 Nanophysics and nanotechnologies INFLUENCE OF THE HYDROGEN INTERCALATION ON THE STRUCTURAL PROPERTIES OF FeTe 0,65 Se 0,35 SINGLE CRYSTAL A.I. Prokhvatilov, S.I. Bondarenko, V.V. Meleshko, V.P. Koverya B. Verkin Institute for Low Temperature Physics & Engineering 47 Nauky Ave., Kharkiv, 61103, Ukraine Single crystal FeTe 0.65 Se 0.35 is one of the new layered iron chalcogenides. Its superconducting properties appear near K [1]. In this work, the single crystal FeTe 0.65 Se 0.35 was with hydrogen saturated in a stainless steel chamber. The idea of hydrogen gas saturation FeTe 0.65 Se 0.35 samples to effect intercalation studies molecular and atomic hydrogen on its structural and superconducting properties. According to [2], saturation with atomic hydrogen is possible as a result of thermal catalytic dissociation on Fe atoms at T 200 C. Hydrogen intercalation into single crystal FeTe 0.65 Se 0.35 was carried out in the temperature range from С at gas pressure Р const =5 atm. Structural studies were carried out on a X-ray diffractometer DRON-3 with К -radiation of Cu with = Å. It was first established that a structural phase transition occurs at a certain temperature and concentration of atomic hydrogen. We believe that the reduction of crystal system of tetragonal to the orthorhombic symmetry of the crystal lattice caused by chemical reaction of H+ ions with atoms of the test compound in the basic planes. It was established that an increase in the temperature in the reaction chamber to 250 C also leads to an increase in the density of crystals due to a change in the parameters of the orthorhombic lattice to values а=3,4928 Å, b=3,4505 Å, c=6,0793 Å, V=73,27 Å, (δv/v=14,6 %) when placed for 5 hours in a hydrogen atmosphere with a pressure of 5 atm. Intensive growth of stresses was usually observed at such a temperature, an increase in the number of roughness steps and, ultimately, the destruction of crystals as a result of stratification by cleavage planes. The structural studies of the hydrogen intercalation of the FeTe 0.65 Se 0.35 single crystal by hydrogen suggest that it should not noticeably affect the superconducting properties of this compound after diffusion of molecular hydrogen at room temperature. In contrast, intercalation with atomic hydrogen, leading to a structural transition and a strong decrease (by 15%) in the crystal cell of the crystal at temperatures of С, should cause a significant change in the electron-phonon interaction and, as a result, a significant change in the compound's superconducting properties. [1] A.G. Sivakov, S.I. Bondarenko, A.I. Prokhvatilov, V.P. Timofeev, A.S. Pokhila, V.P. Koverya, I.S. Dudar, S.I. Link, I.V. Legchenkova, A.N. Bludov, V.Yu. Monarcha, D.J. Gawryluk, J. Pietosa, M. Berkowski, R. Diduszko, R. Puzniak, A. Wisniewski, Supercond. Sci. Technology 30, (2017). [2] K.A. Yagotintsev, I.V. Legchenkova, YU.Ye. Stetsenko, P.V.Zinov'yev, V.N. Zoryanskiy, A.I. Prokhvatilov, M.A. Strzhemechnyy, Low Temp. Phys. 38, 952 (2012)

121 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 119 PHASE STATE, CRYSTAL STRUCTURE OF THIN FILMS OF Fe х Со 1-х ALLOY AND THREE-LAYER STRUCTURES BASED ON IT WITH Cu LAYER D.I. Saltykov, Yu.O. Shkurdoda Sumy State University, Rymsky-Korsakov 2, Sumy, Ukraine Crystal structure, phase and elemental composition of the magnetic layers that are being part of the film system determine the features of its electrical conductivity, magnetic and magnetoresistive properties [1,2]. Thus, the aim of this work is to establish the effect of the structural-phase state and diffusion processes of three-layer film systems based on Fe x Co 1-x (х 0.5) alloy and Cu in a wide range of concentrations and thicknesses. Investigated samples with a thickness of nm were obtained by evaporation and condensation in the vacuum chamber of VUP-5M (at a pressure of 10-4 Pa). Thin-film alloys were formed by fusing pure Fe and Co metals in the required proportion. The films were condensed on a glass substrate with pre-applied copper contacts at room temperature. The deposition rate of the alloy was nm/s. The films were annealed according to the scheme "heating - exposure at temperature of 700 K for 15 minutes - cooling". The study of the structural-phase state was carried out with the help of a transmission electron microscope TEM-125 K. A qualitative analysis of the elemental composition of the films was performed by a secondary-ion mass spectrometry (SIMS) using a mass-spectrometer MS-7201M. The data obtained in the layer-by-layer etching of the film with argon ions were used to construct the concentration profiles along the sample depth. The percentage composition of the film was determined by x-ray microanalysis with energy dispersive spectrometer (EDS). According to the data of electron microscopic and electronographic investigations for both asdeposited and annealed at 700 K Fe х Со 1-х (х 0.5) samples with thickness df nm, their phase composition corresponds to BCC Fe x Co 1-x with lattice parameter a = nm. All films are polycrystalline with a grain of size about 5 nm in as-deposited state) and nm after heat treatment at a temperature of 700 K. Similar results were obtained in [3,4]. In the case of three-layer Fe x Co 1-x /Cu/Fe x Co 1-x /S films with df = nm and dn= 5-20 nm, the phase composition corresponds to the eutectic of the BCC Fe x Co 1-x + FCC s.s. of the Fe and Co atoms in the Cu lattice with a possible isomorphic substitution of Fe and Co atoms regardless of the heat treatment conditions. This is evidenced by the values of lattice parameters. Note that the lattice of Cu (Fe, Co) s.s. has tetragonal distortion, therefore it can be interpreted as the FCT lattice. The results demonstrate that the individuality of the separate layers for two- and three-layer samples after deposition remained regardless of the layer thickness. The negligible blurring of interfaces is a result of the atom diffusion during condensation and ion-stimulated diffusion. Heat treatment of the samples at 700 K does not lead to complete mixing of layers. Insignificant penetration of the second layer elements to the sample surface is probably caused by grain boundary thermodiffusion. This work was funded by the State Program of the Ministry of Education and Science of Ukraine ( ). [1] A.M. Pogorily, S.M. Ryabchenko, A.I. Tovstolytkin, Ukr. J. Phys. Rev. 6, 37, (2010). [2] C.D. Damsgaard, B.T. Dalslet, S.C. Freitas, P.P. Freitas, M.F. Hansen, Sens. Actuators A 156, , (2009). [3] E.M. Kakuno, D.H. Mosca, I. Mazzaro, N. Mattoso, W.H. Schreiner, M.A.B. Gomes, M.P. Cantão, J. Electrochem. Soc. 144, , (1997). [4] D.І. Saltykov, Yu.О. Shkurdoda, І.Yu. Protsenko, J. Nano-Electron. Phys. 10, , (2018).

122

123 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 121 BIOPHYSICS AND PHYSICS OF Biophysics and MACROMOLECULES Physics of Macromolecules

124

125 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine GRAPHENE SINGLE-WALLED CARBON NANOTUBE NANOSTRUCTURES: MOLECULAR DYNAMICS MODELLING 123 M.V. Karachevtsev B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine The interaction of single-walled carbon nanotubes (SWNT) with graphene is able to form nanostructures with significantly improved electrical, mechanical and thermal properties, which make them very useful for huge potential applications including nanoelectronics, nanophotonics, sensors, nanocomposites and so on. We simulated the process of forming the hybrid of SWNT with graphene by molecular dynamics to obtain the energy favorable hybrid structures and to evaluate the interaction between components and to study the influence of water on the interaction between graphene and carbon nanotube. In our calculations, we have used the SWNT of various diameters/chirality and graphene sheet of different geometrical forms (Fig. 1). Molecular dynamics simulation showed that a small narrow sheet of rectangular graphene (460 carbon atoms) has two stable forms on the SWNT surface. After 10 ns of simulation, in the first case, the graphene sheet is located in parallel with the axis of the carbon nanotube, in the second one, the graphene sheet is wrapped around the nanotube. These conformations depend on the diameter of the nanotube, for a nanotube with a diameter of 1.5 nm (SWNT (20.0)), a graphene sheet is wrapped around the nanotube, and for the thinner nanotube with a diameter of 1.2 nm (SWNT (16.0)) the graphene sheet is aligned along the nanotube axis. Another structure has been observed in the complex SWNT with a larger graphene sheet of square shape (5600 carbon atoms). The simulation showed that the interaction between components leads to a slight curvature of the graphene plane, and SWNT shifts from the center to the edge of the graphene sheet. Such nanotube moving occurs due to the acquisition of the most energetically favorable nanotube arrangement on graphene. Other possible 3D nanostructures are formed by two nanotubes with one and two graphene sheets have considered (Fig. 1). The interaction energy of graphene hexagons stacked with the SWNT surface estimated by molecular dynamics simulation has value about -5.3 kcal/mol. It was also shown that in the water environment this energy is approximately 4% less than in vacuum. It should be mentioned that water environment also slows down the acquisition of energetically favorable conformation for the graphene-swnt structure. Fig. 1. Hybrid of SWNTs with a graphene of different forms before molecular dynamics simulation. This work was supported by National Academy of Sciences of Ukraine (Grant N 15/19-H within the program Fundamental Problems of the Creation of New Nanomaterials and Nanotechnology, Grant N and Grant 1/Н D hybrid nanostructures based on 2D nanomaterials (graphene oxide, MoS2): making, characterization and use in sensor devices ).

126 124 Biophysics and physics of macromolecules THE POSSIBILITY OF BLOCKING THE PROCESS OF DNA BASE PAIRS OPENING BY HYDROGEN PEROXIDE O.O. Zdorevskyi, S.N. Volkov Bogolyubov Institute for Theoretical Physics, 14b Metrolohichna Str., Kyiv 03143, Ukraine One of the most progressive methods of cancer treatment is ion beam therapy. Monte-Carlo simulations of water radiolysis [1] show that among many different species occurring in the cell medium, the most long-living are hydrogen peroxide (H 2 O 2 ) molecules. But the role of hydrogen peroxide molecules has not been discussed properly. To understand the possible role of H 2 O 2 in ion beam therapy, the competitive interaction of H 2 O and H 2 O 2 molecules with nucleic bases in a pair on the different stages of genetic information transfer is studied in the present work. Complexes consisting of nucleic base pairs A T and G C with H 2 O 2 and H 2 O molecules are considered. Fig. 1 The most energetically favorable configurations of A T (a) and G C (b) base pairs stabilized by hydrogen peroxide molecules, calculated in the present work. Distances are given in Å. It is shown (Fig. 1) that there are configurations of A T and G C base pairs that are stabilized much better by H 2 O 2 molecule compared to water molecule. As it was shown in the work [2], such states can be observed in unzipping experiments performed by single-molecule manipulation technique. In the present work it was shown, these technique can be used to detect interaction of hydrogen peroxide with nucleic base pairs. Formation of such interaction complexes can terminate the processes of DNA unzipping by enzymes and consequently block genetic information transfer processes in cancer cells during ion beam therapy treatment. [1] D. Boscolo, M. Kramer, M. Durante, M. C. Fuss, and E. Scifoni. Chemical Physics Letters 698, 11 (2018). [2] O. Zdorevskyi, S. N. Volkov European Biophysics Journal, 47, p.917 (2018).

127 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine COMPOSITE FILMS OF SINGLE-WALLED CARBON NANOTUBES WITH GRAPHENE OXIDE: TEMPERATURE DEPENDENCE OF ELECTRONIC CONDUCTIVITY N.V. Kurnosov, V.A. Karachevtsev B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine The hybridization of 1D carbon nanotubes and 2D graphene is able to form 3D nanostructures with significantly improved electrical, mechanical and thermal properties. Along with graphene, water dispersible oxidized graphene (GO) and its reduced form (rgo) are often used to create composites with single-walled carbon nanotubes (SWNT). Potential application fields of such composites include electronics (batteries, supercapacitors), biosensing and drug delivery. The GO-SWNT hybrids were prepared in aqueous suspension, then composite films were obtained by vacuum filtration and characterized using UV-IR absorption spectroscopy, scanning electron microscopy (SEM), computer simulation as well as measurements of electronic conductivity [1]. It should be noted that SWNTs with prevailing content of semiconducting nanotubes (up to 95 %) and graphene oxide with small C:O ratio (about 1.3) were used. Present work focuses on detailed analysis of temperature dependence of electronic conductivity for GO-SWNT composite films and comparison with SWNT film. In experiment, measurements of direct current resistance were carried out during the films cooling and heating, no hysteresis was observed. The average rate of temperature changes was ~(1.5-2) K/min in the temperature range of K. Obtained R(T) dependencies were fitted using such theoretical T models as Arrhenius equation ( R ~ exp( G ) ), fluctuation-induced tunneling (FIT) [2] and variablerange hopping (VRH) [3]. It was found that VRH model gives satisfactory fit in the wide T temperature range of K. At temperatures higher than ~240 K VRH theoretical curve deviated from experimental values, and Arrhenius equation gave better approximation. Evaluated Arrhenius exponential parameter T G was 212 and 130 K for GO-SWNT and SWNT film respectively. VRH model includes dimensionality parameter d and it was found that 3D VRH (d=3) is the case for both SWNT and GO-SWNT films. Also, using results of VRH fit we have calculated such parameters as average hopping distances r and energy barriers W for different temperatures. W was found larger and r was smaller for GO-SWNT film comparing to SWNT one. It may be due to the film composition where GO sheets act as bridges between nanotubes and affect conductivity. It was deduced that conductivity of the composite GO-SWNT film is mainly determined by the conductivity through the nanotubes while GO provides additional barriers, and that both GO-SWNT and SWNT films can be regarded as disordered semiconductor systems. We are grateful to A.M. Plokhotnichenko and A.S. Linnik for help in samples preparation and conductivity measurements. This work was supported by National Academy of Sciences of Ukraine (Grant N 15/19-H within the program Fundamental Problems of the Creation of New Nanomaterials and Nanotechnology, Grant N and Grant 1/Н D hybrid nanostructures based on 2D nanomaterials (graphene oxide, MoS2): making, characterization and use in sensor devices ). [1] V. A. Karachevtsev, A. M. Plokhotnichenko, M. V. Karachevtsev, A. S. Linnik, and N. V. Kurnosov, Low Temp. Phys., accepted manuscript, (2019). [2] P. Sheng, Phys. Rev. B. 21, 2180, (1980). [3] N. F. Mott and E. A. Davis, Electronic Processes in Non-Crystalline Materials (Oxford: Clarendon Press, New York, 1979). 125

128 126 Biophysics and physics of macromolecules CHARACTERIZATION OF SWNT-GO NANOHYBRIDS A.Yu. Glamazda 1,2, S.G. Stepanian, M.V. Karachevtsev, A.M. Plokhotnichenko, V.A. Karachevtsev 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, 61022, Ukraine alex.glamazda@gmail.com We present the complex study of single-walled carbon nanotubes (SWNTs):graphene oxide (GO) nanohybrids by optical spectroscopy (UV-visible optical absorption, Raman spectroscopy) and theoretical calculations. The optical absorption of SWNTs:GO aqueous solution simultaneously reveals the bands corresponding to SWNTs and GO that could be explained by the forming of the nanohybrids. Upon charge transfer from GO to SWNT we observe the suppression of the bands related to the first electronic transition in semiconducting SWNT bands as result of shifting E F. We obtained the energy and structural characteristics of the SWNTs:GO in the aqueous medium by the molecular dynamics. The resulting model structures are characterized by significant binding energy, which is about 400 kcal/mol. The films taken by the vacuum filtration of SWNTs:GO aqueous solution have the layered structure. They are more perspective objects to modeling of elements of nanosensors. The neighboring GO layers create pressure on SWNTs which are arranged between them in the film. That induces shifting of Raman bands related to SWNTs to high-frequency region. The GO layers are undergone a distortion reflected in an increase of Raman D-mode related to GO and performed theoretical calculations. Within the frameworks of the given work we have obtained new experimental and theoretical results on the energy and structural characteristics of SWNTs:GO nanohybrids that have the significant scientific and practical importance and can be used to elaborate the solar cells, batteries and sensitive sensors. A.Yu. Glamazda and M.V. Karachevtsev thank to NAS of Ukraine for financial support (Project 1/H-2019).

129 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 127 INTERACTION OF Zn 2+ IONS WITH SINGLE-STRANDED POLY(C) AND POLY(I) IN A NEUTRAL SOLUTION E.L. Usenko, V.A. Valeev, V.A. Sorokin B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine usenko@ilt.kharkov.ua In alkaline solutions (ph > 8) DNA can transit into the form possessing metallic conductivity which permits to use it upon the design of perspective elements of nanoelectronics [1]. The necessary condition of this transition is the formation of interstrand metallic bridges upon substitutions of iminoprotons of guanine and thymine at single-stranded parts of double helices with transition metal (TM) ions [2]. At the same time the range of effective TM concentrations is limited upon ph > 8. However, it is known that, upon the guanine substitution in GC-pairs with hypoxanthine, metallization with zinc is already observed at ph < 8 [3]. Cooperative formation of single-stranded regions also precedes the formation of a metallized (m) form of DNA in the presence of Zn 2+ ions [2]. Moreover, the presence of single-stranded regions in biological macromolecules is essential for such processes as replication, transcription and translation [4]. Biologically active alkaline earth and transition metal ions can effect these processes. Zn 2+ ions effect on the conformation of poly(c) and poly(i) in cacodylic buffered solution ph 7.0 was studied using differential UV spectroscopy and absorption melting techniques. A three-dimensional phase diagram and its two-dimensional components were constructed for poly(c) Zn 2+ system. The phase diagram revealed a region, in which ordered single-stranded structures are formed being stabilized by Zn 2+ -mediated crosslinks involving N3(C). The phase diagram also demonstrated that behavior of poly(c) Zn 2+ system is similar to the effect of retrograde condensation observed earlier in some binary solutions of simple liquids. The changes in the absorption of poly(i) and its zinc complexes with temperature are stretched over tens of degrees, displaying a non-cooperative melting. This shows that, in contrast to poly(c), poly(i) has a singlestranded disordered conformation throughout the whole studied range of temperature and Zn 2+ concentrations. The atoms coordinating Zn 2+ ions were determined (N1 and N7 in poly(i) and N3 in poly(c)). A dependences of Zn 2+ binding constant to poly(i) and poly(c) atoms on the metal ion concentration have been obtained. It was shown that Gibbs free energy of Zn 2+ binding to N7 and N1 of poly(i) and N3 of poly(c) is a linear function of the binding degree. It is characterized with positive cooperativity conditioned mainly by dehydration of ions and bases upon the formation of metal complexes. Higher cooperativity of Zn 2+ binding to N1 atoms is conditioned by the fact that the increase of N7 metallization degree lowers the constant of N1 protonation and promotes the substitution of iminoprotons with zinc ions. [1] Sh. D. Wettig, C.Z. Li, Y.T. Long, H.B. Kraatz, and J. S. Lee, Anal. Sci. 19, 23-26, (2003). [2] V.A. Sorokin, V.A. Valeev, E.L. Usenko, and V.V. Andrushchenko, Int. J. Biol. Macromol. 50, , (2012). [3] D.O. Wood, M.J. Dinsmore, G.A. Bare, and J.S. Lee, Nucleic Acids Res., 30, , (2002). [4] Ch. Ke, A. Loksztejn, Y. Jiang, M. Kim, M. Humeniuk, M. Rabbi, and P. E. Marszalek, Biophys J. 96, , (2009).

130 128 Biophysics and physics of macromolecules H-AGGREGATION OF THE NOVEL TRIMETHINE CYANINE DYE AS AN INDICATOR OF INSULIN AMYLOID TRANSFORMATION U.T. Tarabara, K.O. Vus, O.A. Ryzhova, V.M. Trusova V.N. Karazin Kharkiv National University,4 Svobody Sq., Kharkiv, 61022, Ukraine Сyanine dyes, a wide class of compounds with unique photophysical properties, have found numerous applications in different areas as optical imaging agents, active ingredients in semiconductor materials, laser dyes, photographic sensitizers, photopolymerization initiators, stains and fluorescent labels, to name only a few [1]. These compounds are of particular interest for biomedical research and diagnostics due to their favorable spectral characteristics, namely, long wavelength absorption and emission, large extinction coefficient, high fluorescence quantum yield, etc. [2]. During the past decade cyanines attract special attention due to their ability to differentiate between the native and pathogenic aggregated conformational states of the protein molecules. The aggregation of soluble proteins into highly ordered structures, termed amyloid fibrils, is a key factor in etiology of a number of severe disorders, including Alzheimer s, Parkinson s, Huntington s diseases, type II diabetes, etc. The most widespread fluorescence criterion for identification of amyloid fibrils is based on the use of fluorescent dye thioflavin T (ThT) whose emission is drastically enhanced upon its complexation with fibrillar structures. However, despite being prevalent, ThT assay is not devoid of shortcomings. For these reasons, there exists a strong need in designing and experimental testing of new fluorescent compounds for amyloid sensing. The aim of the present study was two-fold: (i) to characterize the ability of the newly synthesized near-infrared cyanine trimethine dye, AK3-3, to selectively recognize the amyloids fibrils, and (ii) to perform comparative analysis of the spectral behavior of AK3-3 bound to native and fibrillar insulin. Insulin, used here as a model protein, is a small hormone regulating the glucose homeostasis and lipid metabolism, that is capable of forming fibrils under denaturing conditions such as elevated temperatures, low ph, the presence of organic solvents, agitation, etc. Insulin amyloid deposits are a preclinical sign of injection-localized amyloidosis in diabetic patients, and these species were observed in Parkinson s disease, as well. Furthermore, amyloid fibrillation is a limiting factor in production, long-term storage and delivery of insulin pharmaceutical formulations. Insulin amyloid fibrils were obtained in vitro by the protein incubation in glycine buffer (ph 2) at 37 ºC under continuous shaking for 6 days. The absorption spectra of AK3-3 were recorded in an organic solvent, dimethyl sulfoxide (DMSO), and in 5 mm sodium-phosphate buffer (ph 7.4) in the presence of the native or fibrillar insulin, referred to here as InsN and InsF, respectively. It was found that AK3-3, similar to other cyanines, undergoes H-aggregation in the aqueous media. H-aggregates are composed of the dye molecules stacked face-to-face, accompanied by the hypsochromic shifts of the absorption spectra relative to the monomer band [3]. The analysis of the spectral line shape showed that AK3-3 absorption spectra in buffer and in InsN can be decomposed into two components, while in InsF into the three components, described by the asymmetrical LogNormal function, that were attributed to the dyes monomers, H-dimers and higher order H- aggregates. The main difference between InsN and InsF lies in the significantly higher contribution of the aggregated dyes in the overall spectrum, suggesting that amyloid fibrils can serve as a template for the assembly of H-aggregates. In conclusion, our findings are expected to open new possibilities for the use of cyanine dyes for the detection and characterization of amyloid fibrils. [1] J.L.Bricks, at al. Dyes and Pigments. 121, 238 (2015). [2] H.A. Shindy. Dyes and Pigments. 145, 505 (2017). [3] A. Eisfeld, et al. Chem. Phys. 324, 376 (2006); Y. Yamada, et al. Inorg. Chem. Acta. 43, 275 (1998).

131 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine INTERACTIONS OF BIOGENIC AMINES AND SYNTHETIC QUATERNARY AMMONIUM COMPOUNDS WITH GRAPHENE OXIDE V.G. Zobnina, O.A. Boryak, M.V. Kosevich B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine The aim of the present work was to investigate intermolecular interactions in the nanosystems composed of biogenic polyamines, synthetic bisquaternary ammonium compounds and graphene oxide (GO) nanomaterial. The objects of the study were selected basing on their important biological functions: polyamines play regulatory role in biosynthesis of biopolymers and functioning of nervous system; a number of chemotherapeutic drugs is based on bisquaternary ammonium compounds; new useful properties are expected from combining of biologically active compounds with nanomaterials in nanocomposites. To study complexation and intermolecular interactions in the binary systems containing GO, its water suspension was mixed with spermidine (H 2 N-(CH 2 ) 4 -NH-(CH 2 ) 3 -NH 2 3HCl) or putrescine (H 2 N-(CH 2 ) 4 -NH 2 2HCl) biogenic amines and synthetic drugs based on bisquaternary ammonium compounds decamethoxinum or ethonium. Flakes formation and coagulation of the initially homogenious suspension of GO were observed on addition of amines; their extent was dependent of M Spd M Spd +0M Spd M Spd M Spd M Spd Fig. 1. Transformations in aqueous suspensions of GO mixed with spermidine (Spd) in the concentration range M. Fig. 2. Scheme of possible connection of GO sheets by polyamines with positively charged functional groups. 129 the amine concentration, as illustrated by example of GO-spermidine system shown in Fig. 1. Formation of such layered or resin-like structures and their separation from the aqueous phase is characteristic of all studied systems. This observation has a number of consequences. It is obvious that GO can be employed for purification of water from amines; on the contrary, amines are able to collect the GO sheets from solution to a separate phase. At the same time, 3D structures composed of GO and organic compounds are formed due to GO interactions with amines. Possible mechanisms of formation of the structures observed are discussed. Several positively charged sites are formed in polyamines due to protonation of amine groups in aqueous medium, while quaternary ammonium groups bear pre-formed positive charges. Binding of several GO sheets by polyamines can occur due to interactions of the different positively charged groups of a single molecular ion with negatively charged oxygencontaining groups on different GO sheets. The dependence of the binding efficiency on the distance between the charged groups of polyamins is discussed. Mass spectrometric measurements of the polyamines in the composites were performed. The observed effects may be accounted in further elaborations of composites of GO with biomolecules containing protonated amine and quaternary ammonium groups.

132 130 Biophysics and physics of macromolecules DIELECTRIC PROPERTIES OF NANOPARTICLE SUSPENSIONS AT LOW TEMPERATURES: A THERMODYNAMIC OF SOLUTION HYDRATION L.V. Batyuk 1, O.M. Morozova 1, N.N. Kizilova 2 1 Kharkov National Medical University, 4 Nauki Ave., Kharkiv, 61022, Ukraine liliyabatyuk24@gmail.com oksanabakan2012@gmail.com 2 Warsaw University of Technology, Pl. Politechniki 1, Poland, 00661, Warsaw n.kizilova@gmail.com Modern direction of nanomedicine is creation of complex biocompatible nanomaterials that promote the targeted drug transport to the place of localization of pathological process [1]. As known, suspensions of nanoparticles (NP) to be the best candidates which possess unique structural characteristics and unusual mechanical, electrical, thermal and biological properties [2], [3]. Biological compounds of NP are suspensions groups of micoparticles like cells with the extremely high thermal conductivity of the in comparison to the base fluid. The dielectric behavior of particles can be simulated by taking into account the spherical and ellipsoidal shape dependences of the surface and volume. The purpose of the investigation is build a model that can account in a unified way for the dielectric response of NP in suspensions in the formalism of Kluitenberg s theory, and later to derive the expression of the complex dielectric function that generalizes the one of Debye. The Kluitenberg's idea consists in the assumption that there is a vector field ῼ which plays the role of thermodynamic internal degree of freedom and which influences the polarization [4]. As an example were comparing the results obtained with experimental data. Based on this model, we have analyzed the effect of temperature on the dielectric dispersion curves of red blood cells in suspension. The hydration shell of NP is heterogeneous with respect to fractional composition. The approximate values of H and S can be estimated based on the assumption that the two structural species of liquid water can be approximated. The temperatures changed are influence the polarization of the NP. It is conceivable that this behavior corresponds to an decrease in the relaxation time, i.e. the lower the temperature the higher the polarization process. This is normally formulated by an activation process for the relaxation time, of the type independent entities and corresponds to the Debye model. All the parameters of the model have distinct influences on the dispersion curves, a fact that lead us to conclude that all the parameters can be accurately obtained by fitting experimental data with our model. [1] L. Batyuk and N. Kizilova, AS Cancer Biology. 2, 10, 55-60, (2018). [2] L. Batyuk and N. Kizilova, Book of Abstracts, RAD-2018, 267 (2018). [3] S.G. Kandlikar, S. Garimella, D. Li, S. Colin, and M.R. King, Heat transfer and fluid flow in minichannels and microchannels (Elsevier, Singapore, 2006). [4] G.A. Kluitenberg, Physica A 109, 91 (1981).

133 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 131 MATERIALS SCIENCE Materials Science

134

135 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine MODELLING OF INTERACTION BETWEEN BASAL STACKING FAULTS AND TWIN BOUNDARIES IN MAGNESIUM A. Ostapovets 1, A. Serra 2, R.C. Pond 3 1 Central European Institute of Technology - Institute of Physics of Materials (CEITEC IPM), Academy of Sciences of the Czech Republic, Žižkova 22, Brno, Czech Republic 2 Department of Civil & Environmental Engineering, Universitat Politecnica de Catalunya, Jordi Girona 1-3, Barcelona, Spain 3 College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, EX4 4QF, United Kingdom ostapov@ipm.cz Magnesium and its alloys are prospective low weight materials. Magnesium has hcp crystal structure. Deformation of hcp materials is often accompanied by mechanical twinning [1,2]. Consequently, the study of twin boundary migration mechanisms is important for a better understanding of the deformation behaviour of magnesium. Since a high density of basal stacking faults is often observed inside deformation twins [3-5], it is important to establish whether these serve as obstacles for twin growth, and thereby affect the mechanical properties of the material. We analyze the interaction of a basal stacking fault with a twin boundaries in magnesium investigated using atomistic simulations. The defect delineating the interaction is characterised as an imperfect disconnection. In addition, we analyze the reaction which occurs between such defects and mobile twinning disconnections during twin growth. [1] A. Ostapovets, R. Gröger, Modell. Simul. Mater. Sci. Eng., 22, , (2014). [2] A. Ostapovets, J. Buršik, R. Gröger, Phil. Mag., 95, , (2015). [3] A. Ostapovets, A. Serra, Phil. Mag. 94, , (2014). [4] H. El Kadiri, C.D. Barrett, J. Wang, C.N. Tome, Acta Mater., 85, , (2015). [5] Q. Sun, X.Y. Zhang, R.S.Yin, Y. Ren, L.Tan, Scripta Mater., 108, , (2015). 133

136 134 Materials science STRUCTURAL TRANSITIONS IN ORGANIC CRYSTALS E.N. Trotskiy 1, V.A. Lykah 2, E.S. Syrkin 3 1 V. N. Karazin Kharkiv National University 4 Svobody Sq., Kharkiv, 61022, Ukraine 2 National Engineering University Kharkiv Polytechnic Institute 2 Kirpichov St., Kharkiv, 61002, Ukraine 3 B. Verkin Institute for Low Temperature Physics and Engineering of the NAS of Ukraine Nauki Ave., 47, Kharkiv, 61103, Ukraine e.trotskiy94@gmail.com In complex organic crystals various physical properties can exhibit at low temperatures, including structure and electron ones [1]. Structured and charge ordering in the crystal depend on cooling rate. In present report we propose the simple model, which can describe phase transition from disordered to ordered phases in considered system. Consider a one-dimensional model of a crystal where flat organic molecules are in contact with their wide planes. An example of such molecules is the BEDT molecule and crystal, in which charge ordering is possible with the addition of small molecules of a different sort. We assume that the plane of the molecules is perpendicular to the direction of the one-dimensional chain. This assumption corresponds to a lot of experimental data [1]. The interaction between the planes of molecules has a complex form, but we assume that it is determined by the Lennard-Jones potential for large molecules r0 r0 Ur ( ) 2 (1) r r Where r 0 is the equilibrium distance between large molecules, and ε is the depth of the potential well. Let the small molecule occupy a position between large ones. For the interaction of small molecules with each other and with a large molecule, we use the formula (1) with the replacement of r 0 by r s. It is shown that when the parameter s rs / r is varied, there is first a double-well potential in 0 the interval 0 s 0.44, which decreases with increasing s, and for s > 0.44, the barrier between the wells disappears. For a more accurate analysis, we use the potential s first derivative in r, which is more sensitive to the confluence of the potential extremes. Small molecules shift the equilibrium position between large ones and the distance changes. We consider the position of a large molecule at the point 0, and the second at point r 0. We will find the new position of the second molecule with the simultaneous action of large and small molecules. To do this, expand the potential near the coordinate r 0 : U s 2s 12 ( s s ) 36 1 ; r r0 (1 ) (2) The minimum condition U / =0 to the following equilibrium position: 6 12 e ( s s ) / 6 0. That is, when introducing a small molecule, large molecules should additionally attract each other, the period of the molecular chain decreases. In a chain of large molecules, small molecules fill every gap between large molecules. It was shown that if all molecules are electrically neutral, then at low temperatures a structural phase transition occurs: small molecules group in pairs near a large molecule, the lattice period doubles. In case of charged molecules, the charge-ordered state appears. At high cooling rate, disordered distribution of small molecules in double-well potential arises. [1] Kagawa F., Oike H. Advanced Materials 29, 25, p (2017).

137 , MPa X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine THE EFFECT OF NANOSCALE GRAIN SIZE ON THE STRAIN RATE SENSITIVITY AND ACTIVATION VOLUME IN TITANIUM AT LOW TEMPERATURES R.V. Smolianets, V.A. Moskalenko B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine smoljanets@ilt.kharkov.ua For identification of the controlling physical mechanisms of the plastic flow crystals special attention is paid to the measurement and analysis of parameters such as sensitivity to strain rate and activation volume- characteristics of the kinetics of the plastic flow process. In this work we studied the effect of nanoscale grain size on the strain rate sensitivity and the activation volume of technical purity titanium VT1-0 in the temperature range K. Nanocrystalline (NC) titanium with an average grain size d 35 nm was produced by using multiple rolling at the temperature of liquid nitrogen [1].The materials with the grains of d 45 nm and 2 μm was obtained by using the subsequent annealing. The samples were deformed by uniaxial tension with a change of the strain rate in five times to the base rate. In Fig. 1 shows the temperature dependences of the strain rate sensitivity = ( ln τ) T (Fig. 1a) and the activation volume V * = kt( ln τ) T = kt/ (Fig. 1b) for samples with different grain sizes. It is seen that the character of the dependence (T) for NC titanium have similar to coarse-grained (CG) samples. In comparison with CG titanium (d = 2 μm), the value of NC samples increases in 1,7 times for d 35 nm and 1,5 times for d 45 nm. It is important to note that the relative variation of the strain rate sensitivity with decreasing grain size CG / NC have independent of the temperature a) d = 35 nm d = 45 nm d = 2 mcm V *, b b) d = 2mcm d = 45 nm d = 35 nm Fig. 1. Temperature dependences of the strain rate sensitivity (a) and the activation volume V * (b) Т, К T, K The activation volume V * of plastic deformation process is reducing from 36 b 3 (CG titanium) to 21 b 3 (NC titanium, d 35 nm) at T = 293 K. It is well known that the rate of plastic deformation in CG technical purity titanium is controlling by thermally activated overcoming dislocations of local barriers created by impurity interstitial atoms (oxygen, nitrogen) [2]. In NC titanium the concentration of controlling impurity is not changed. Therefore, the length of the dislocation segment l which takes part in a local activation event is equal to the average distance between impurities in the slip plane (according to the Friedel statistics for strong barriers) must be saved in NC titanium. In this case, the observed decrease of the activation volume V * = bw(τ)l is associated with the influence of the grain size on the activation distance w(τ). It is assumed that the controlling plastic deformation mechanism of NC titanium VT1-0 (similarly to CG titanium) is associated with thermally activated overcoming dislocation of local barriers related to the presence of impurity atoms. [1] V.A. Moskalenko, A.R. Smirnov, A.V. Moskalenko, Low Temp. Phys. 35, 905 (2009). [2] V.N. Kovaleva, V.A. Moskalenko, and V.D. Natsik, Philos. Mag. A70, 423 (1994).

138 MPa GPa MPa MPa 136 Materials science INFLUENCE OF GRAIN SIZE ON TWINNING DURING LOW TEMPERATURE PLASTIC DEFORMATION OF AZ31 ALLOY P.A. Zabrodin B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine The plastic deformation of polycrystals of magnesium alloy AZ31 with microstructures after severe plastic deformation (state A) and annealing (state B) deformed in tension at a temperature of 4.2 K was studied. The average grains size of A samples is d А 0.8 μm, and the average dislocation density ρ A inside the grains is of the order of ρ A m -2. The microstructure parameters for B samples is d B 0.8 μm and ρ B m -2 [1]. In the polycrystals, subjected to severe plastic deformation, a specific crystallographic texture was formed. It is established that, regardless of the microstructure, the plastic flow is discontinuous exhibiting stress jumps, whose amplitude increases with increasing strain. With increasing grain size due to annealing, the strength of polycrystal decreases, its plasticity increases, and the discontinuous plastic flow is partially suppressed (the jump amplitude is reduced or even disappears). An analysis of the discontinuous flow statistics showed that for ultrafine grained polycrystals the frequency distribution of the stress jump amplitudes is more sharp than that for coarse-grained counterparts Fig. 1. True stress true strain A 20 B a) b) 16 curves for A and B samples (figure 1.a), inset dependence of 8 the strain hardening rate θ on the ,02 0,04 0,06 0,08 0,10 strain ε. Dependence of the amplitude Δσ on the strain ε for 2 B 6 c) structure A - (figure 1.b) and for A structure B - (figure 1.c). 0,00 0,05 0,10 0,15 0,00 0,05 0,10 0, ,02 0,04 0,06 0,08 0,10 The results of the experiments are discussed employing the concept of the avalanche-like dynamics of dislocations being the cause of discontinuous plastic deformation under conditions of low temperatures and high stresses. One of the conditions for discontinuous flow is a high (threshold) density of dislocations, the evolution of which with strain is described by work hardening coefficient θ( ) [1,2]. In our case, when comparing data of samples A and B, it can be seen that a rapid decrease of θ with strain for sample A correlates with a rapid increase of the amplitude. This correlation is obviously explained by the high initial dislocation density in the fine-grained sample A as compared to its coarse-grained counterpart B. With small deformations, in the case of structure B, a positive hardening region (insert on fig.1,a) and deformation independent jumps (fig.1,c) was observed. It is inconsistent with the theoretical assumptions of the influence of the grain size and the dislocations density on the low temperature plastic deformation and instability, and is apparently due to the enhancement of twinning in the annealed polycrystal. [1] N.V. Isaev, S.E. Shumilin, P.A. Zabrodin, M. Janeček, J. Stráská, Acta Physica Polonica A. 134, 662 (2018). [2] B. Skoczen, J. Bielski, S. Sgobba, and D. Marcinek, Int. J. Plasticity 26, 1659 (2010).

139 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine INVESTIGATION OF THE ACOUSTIC PROPERTIES OF NANOSTRUCTURED MATERIALS AT LOW TEMPERATURES 137 O.M. Vatazhuk B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine Ultrafine grained and nanostructured metals and alloys are of great interest in solid state physics as objects for studying the mechanisms of motion of dislocations in conditions of high density of effective obstacles. The source of valuable information on the parameters of the dislocation structure of metals is an experimental study of their dynamic elastic and inelastic properties in a wide temperature range by acoustic spectroscopy methods that have high sensitivity to structural parameters change, selectivity, reproducibility, and, moreover, are non-destructive measure of measurements. The elastic and inelastic properties of nanostructured materials at low temperatures, as well as the physical mechanisms that determine these properties, are still poorly understood. Of primary interest is the question of the effect of the grinding of the grain structure on the low-temperature relaxation resonances inherent to coarse-grained metals. It was found for the first time that the peaks of internal friction found in nanostructured copper and highly fragmented nanostructured fibrous composite Cu-Nb are determined by the lowtemperature dynamics of the movement of dislocation segments in the primary and secondary copper and copper matrix Peierls. It is also shown that the relaxation of internal friction near 250 K, detected earlier in the coarse-grained annealed Zr, remains after severe plastic deformation, but its height increases by about 10 times, and the localization temperature shifts to low temperatures. In addition, after severe plastic deformation, a new peak of internal friction was registered for the first time in the region of moderately low temperatures near 80 K. The insufficient stability of the structures of the ultrafine grained and coarse-grained of samples created by applying various severe plastic deformation schemes was established. The temperature dependence of the Young's modulus of the nanostructured samples revealed a characteristic of low-temperature elastic moduli of glasses as a result of the interaction of acoustic oscillations with dislocation two-level systems, relaxation systems, and harmonic oscillators. It is hypothesized about the dislocation nature of the glass subsystem (or phase ) in nanostructured metals obtained by severe plastic deformation.

140 H V, МPа 138 Materials science LARGELY ENHANCED MECHANICAL PROPERTIES OF GRAPHENE OXIDE/POLYESTER RESIN NANOCOMPOSITES H.V. Rusakova 1, L.S. Fomenko 1, S.V. Lubenets 1, A.V. Dolbin 1, N.A. Vinnikov 1, R.M. Basnukaeva 1, M.V. Khlistyuck 1, A.V. Blyznyuk 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 National Technical University "Kharkiv Polytechnic Institute", 2 Kyrpychova Str., Kharkiv 61102, Ukraine rusakova@ilt.kharkov.ua Improvement in mechanical characteristics of polymers can be achieved by introducing of high-strength carbon nanoparticles, among them graphene and its oxide with unique strength and Young modulus, as reinforcing nanofillers. Here the object was to synthesize the following nanocomposites: polyester resin (PER)-graphene oxide (GO) and polyester resin-glass fibre (GF)- graphene oxide (Table); as well as to measure Vickers microhardness H V of these composites for the purpose of revealing of the filler strengthening role. Graphene oxide was prepared by exfoliation of graphite oxide produced by the modified Hummers method. The structure, morphology and elemental composition of the produced graphene oxide were investigated by scanning and transmission electron microscopy and energy-dispersive X-ray spectroscopy. The nanocomposites were produced by ultrasonic dispersion of graphene oxide in the liquid polymer. The microindentation was performed in the temperature range of К, the impressions sizes were measured after heating up to the room temperature. The qualitative difference of the mechanical properties of PER-0.3 wt. % GO nanocomposite and pure PER was revealed. At room temperature PER behaved as elastomer (microhardness impressions were fully recovered after unloading), whereas the nanocomposite showed the glassy properties (the impressions were retained) PER-GF 2 - PER-GF-0.5 wt. % GO 3 - PER-GF-1 wt. % GO 0,05 0,10 0,15 Р, N T = 300 K Table. The temperature ranges of residual impressions observing and microhardness measuring Material T, К PЕR elastomer at T = 300 K PER-0.3 wt. % GO PER-GF PER-GF-0.5 wt. % GO PER-GF-1 wt. % GO It was shown that the introduction of GO in PER-GF resulted in strengthening of the composite in the whole studied interval of the indentation load Р = N (figure). At Р = 0.15 N the microhardness increased on 20 % and 80 % for 0.5 and 1 wt. % GO respectively. For the PER-0.3 wt. % GO nanocomposite microhardness was measured in over all temperature range of К (Table). However for the PER- GF, PER-GF-0.5 wt. % GO and PER-GF-1 wt. % GO samples the deformation reversibility was occurred as the temperature decreased to 244 K, K and 189 К respectively. This effect is evidently caused by the forming of crazes (fibrillar-porous nanostructures) [1]; their glass-transition temperature can be tens of degrees below that of bulk polymer. [1] A.L. Volynskii and N.F. Bakeev, Solvent Crazing of Polymers, Elsevier, Amsterdam (1995).

141 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine POROUS SODIUM-RICH CALCIUM PHOSPHATE CERAMICS 139 N. Mielnik, A. Goncharenko, Z. Zyman V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, 61022, Ukraine nata.melnik1998@gmail.com One of the most difficult problems of modern traumatology and maxillofacial surgery is the development of biomaterials that are similar by the chemical and phase composition, mechanical and biological properties to human bone tissue. It was found that ceramics based on calcium phosphates (CP) are most appropriate for this purpose [1]. CP ceramics cause no adverse clinical effects (for example, inflammation or rejection of the implant). In addition, this material exhibits bioactive properties, such as bioconductivity and sometimes even bioinductivity. The pores provide larger contact area between the CP bioceramics and bone tissue. It results in the formation of more chemical bonds. Due to this, bone tissue grows into the implant more effectively. Porous CP bioceramics are usually fabricated from natural or synthetic initial materials. The first are materials of natural origin, such as corals or bones of living organisms. The application of natural materials has a number of disadvantages associated with biological variability and viral or bacterial risk of infection. The second type are synthetic materials. They are good alternative to natural grafts and widely used as bone substitutes. Since sodium is one of the most common substituting elements in human bone and bone is the main reservoir of sodium in a living organism, studying porous CP ceramics containing sodium is actually promising [2]. The purpose of this work was to create porous sodium-rich calcium phosphate ceramics, to reveal the influence of heat treatment conditions on the phase structure and porosity of the final product. As a starting material for fabrication of porous ceramics, a mixture of β-tricalcium phosphate, β-ca 3 (PO 4 ) 2, β-tcp powder and polystyrene as pore-forming component was used. Polystyrene spheres were 1 mm in diameter. β-tcp was derived by precipitation from the a variation of the nitrate synthesis. Some deionized water was added to the mixture. The resulted paste was formed into cylindrical samples. They were dried at 60 C overnight and then sintered at a temperature of 900, 1000, 1100 and 1200 C for 3.5 hours. After cooling, the ceramic samples were degased in vacuum, soaked in 35% solution of NaNO 3, dried and re-annealed at the same temperature for 1 hour. Porosity, morphology, phase and impurity composition of the initial and soaked samples were examined. As a result, biphasic (hydroxyapatite, HA, Ca 10 (PO 4 ) 6 (OH) 2, and rhenanite, Rh, NaCaPO 4 ) or threephasic (HA, Rh and β-tcp) porous ceramics were obtained depending on the heat treatment conditions. The porosity of the ceramics was %, which is similar to the value in trabecular bone. The ceramics had a gradient structure. The gradient peculiarity in phase composition in a porous sodium-rich calcium phosphate ceramic annealed at 1100 C for 1 hour was detailed. [1] F.Stergioudi, A.Choleridis, E.Paulidou, E.Smyrnaios, N.Michailidis. Ceram. Inter. 41, , (2015). [2] E. Champion. Acta Biomat. 9, , (2013).

142 140 Materials science KINETIC AND MECHANICAL PROPERTIES OF THE HIGH-ENTROPY ALLOY Аl 0.5 CoCuCrNiFe AT LOW TEMPERATURES E.S. Savchuk, V.A. Frolov, V.I. Sokolenko, M.A. Tikhonovskij, E.V. Karaseva National Science Center Kharkov Institute of Physics and Technology 1, Academichna St., Kharkiv, 61108, Ukraine Most studies of the high-entropy alloys (HEA) are devoted to the technological aspects of their preparation and the study of structure using modern methods [1]. It seems that for solution of the problem of optimizing the HEA properties required for practical purposes may be useful using the electro-physical methods that are not sufficiently used in most of the works. In this report the presence of a number of anomalies in the temperature dependences of the kinetic coefficients that characterize the transfer of electric charge and heat are demonstrated on the example of the alloy Аl 0.5 CoCuCrNiFe (cast and annealed samples). The correlations of these features with the anomalies of mechanical properties and dissipative properties known from the literature [2,3] are shown. The temperature interval of ~ K, in which the correlation of the anomalies of all studied characteristics (the specific electrical resistivity (ρ), the absolute thermoelectric power (S), the derivative of thermal conductivity (dk/dt) and creep rates)) is observed, is the most interesting for a scientific point of view and also is important for practice. In this range, the anomalies in the ρ(t) dependence are weakly expressed but the temperature dependences S(T) and dk(t)/dt have minima, and the creep rate changes by a factor of 2-3, what is consistent with the literature data [3,4], where the acoustic properties of the Аl 0.5 CoCuCrNiFe alloy were studied. After the annealing of the specimens at 975 C in the course of 12 hours the values of ρ 300 К and S 300 К has decreased by ~ %, but the dependences ρ(t), S(T) and dk(t)/dт has having all the same temperature anomalies. The study of the electro-physical and thermal properties of the samples deformed under creep conditions at 300 K to stresses σ 0.9σВ did not reveal any changes in the positions of the kinetic coefficients anomalies on temperature scale. The observed features of the physics-mechanical characteristics of the Аl 0.5 CoCuCrNiFe alloy may be related with the structural-phase transformation, martensite type apparently, happening by lowering temperature in the temperature range of ~ K. To the nature elucidation of the effect discovered it is necessary the conducting of structure investigations. The results obtained should be taken into account by designing the systems the Аl 0.5 CoCuCrNiFe contained which must operating under thermal cycling conditions in the temperature range studied. [1] J.W. Yeh, Y.L. Chen, S.J. Lin, S.K. Chen. Mater. Sci. Forum 560, 1 (2007). [2] M.A. Laktionova, E.D. Tabachnikova, Z. Tang and others. FNT 39 No. 7, 814 (2013). [3] Yu.A. Semerenko, E.D. Tabachnikova, T.M. Tikhonovskaya. Metal physics and the latest technology. 37, No. 11, 1527 (2015). [4] A.S. Bulatov, V.S. Klochko, A.V. Korniyets, I.V. Kolody, T.Yu. Rudycheva, V.I. Spitsyna, M.A. Tikhonovsky, A.S. Cake XII international conference Physical manifestations in solid tits, Kharkov, 2015, p.89.

143 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine MECHANICAL AND DISSIPATIVE PROPERTIES OF VT6 ALLOY WITH NANOMETER SCALE STRUCTURES OBTAINED BY CRYODEFORMATION METHODS N.A. Shulgin, V.I. Sokolenko, A.V. Mats, V.S. Okovit, P.A. Khaimovich National Science Center Kharkiv Institute of Physics & Technology of NAS of Ukraine, 1, Academichna St., Kharkiv, 61108, Ukraine Titanium alloy VT-6 with ultrafine-grained (UFG) structure was obtained by isothermal forging (ITF) in the mode of 700 C to 650 C to 600 C (IPSM RAS, Ufa). As a result of subsequent deformations at T=77 K (cryogenic rolling, CR, and quasi-hydroextrusion, QHE) nanometer-scale structures (NS) were formed (Fig. 1) and additional hardening was achieved (up to 25%) with a slight decrease in the plasticity margin. 141 Fig.1. The structure of the alloy VT6: a - UFG state; b and c - the NS state after QHE ( 20%) and CR ( 60%), respectively. The optimal degrees of deformation are established and substantiated, the excess of which causes the occurrence of microcracks and limits the level of the deformation dispersion of the alloy. Fig.2. The dependence of the yield strength on QHE strain. The temperature dependence of the low-frequency (~0.4 Hz) internal friction δ and shear modulus G was measured in the amplitude independent region ( = ). There are in the NS state (CR, =60%, and QHE, =20%) the wide peaks in the form of a superposition of several components on the δ(t) dependencies at K and K. They are associated with relaxation processes caused by the movement of dislocations in an alternating stress field in the presence of point defects. A significant increase in δ at elevated temperatures (T>510 K and T> 470 K, QHE and CR, respectively) in the NS state was observed (Fig.3) Fig.3. Dependencies (T): 1 UFG; 2 NS (CR, =60%); 3 QHE ( =20%) T,K For the NS state in the investigated temperature range ( K), a significant decrease in the shear modulus compared with the UFG state is characteristic. The processes of structural changes and the possible mechanisms of the observed effects are discussed.

144 142 Materials science EFFECT OF CRYO-DEFORMATION BY REPETITIVE UPSETTING EXTRUSION ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF CoCrFeMnNi HIGH-ENTROPY ALLOY A.V. Levenets, A.S. Kalchenko, M.A. Tikhonovsky, P.A. Khaimovich National Science Center, Kharkov Institute of Physics and Technology, 1 Akademicheskaya Str, Kharkiv 61108, Ukraine avlevenets@gmail.com Severe plastic deformation methods are widely used for effective control microstructure and properties of metallic materials. One of such methods is to use repetitive upsetting- extrusion (or extrusion - upsetting) processing, that can repeat many times (cyclically). This method was developed at National Science Center Kharkov Institute of Physics and Technology of NAS of Ukraine [1] and has proven its efficiency in preparing ultra-fine grain materials with unique physical and mechanical characteristics in laboratory conditions as well as in industrial conditions [1,2]. It has to be noted, that upsetting and extrusion processing was preparing either at room or elevated temperature. It was of interest to test this technology in conjunction with cryo-deformation methods, which allow to obtain additional structure dispersion due to lowering temperature of plastic deformation [3]. Well-known CoCrFeMnNi high-entropy alloy (known as Cantor alloy), which exhibits remarkable ductility at cryogenic temperature, was as an object of investigation. In this study, origin blank alloy in the form of cylindrical rods with 10 mm in diameter and 20 mm in height was extruded by barocryodeforming [3] at 77 K by 22%, followed by upsetting by the same extent at 77 K. Such cycle was repeated twice, and samples for electron microscopic analysis and microhardness measurements were cut off perpendicular to cylinder axe after each pass. Features of formed microstructure were studied and a significant rise in hardness during upsetting extrusion processing at cryo temperatures was found. [1]. I.I. Papirov, G.F.Ttikhinsky. Modern investigation of the beryllium. Garinizdat Kharkov, [2]. M.A. Tikhonovskiy, G. Shepelev, L.V. Panteyenko VANT. Seriya «Vakuum, chistyye materialy, sverkhprovodniki». 2003, 5 (13), с [3]. P.A. Khaimovich. Metal Nanostructuring through Cryodeformation under All-Round Compression. "Handbook of Mechanical Nanostructuring". Published 2015 by Wiley-VCH Verlag GmbH & Co. KGaA. pp

145 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine CRYSTAL STRUCTURE AND PHYSICOCHEMICAL PROPERTIES OF ORGANIC-INORGANIC HYBRID COMPOUNDS: (NH 2 CHNH 2 ) 3 [Bi 2 Cl 9 ] AND (NH 2 CHNH 2 ) 3 [Bi 2 Br 9 ] K. Mencel 1, P. Srarynowicz 1, M. Siczek 1, A. Piecha-Bisorek 1, R. Jakubas 1, W. Medycki 2 1 Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, Wrocław, Poland 2 Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, Poznań, Poland klaudia.mencel@chem.uni,wroc.pl There is a surge of interest in development of new organic-inorganic ferroelectric materials suitable for technical applications (e.g. in optoelectronics, switchable dielectric devices, data communication storage), which may be competitive with the perovskite hybrids based on lead. Recent achievements in this field have shown that haloantimonates(iii) and halobismuthes(iii) with akylammonium and heteroatomic cations create an extremely promising group of ferroic crystals due to their nonlinear electric and optical properties [1-4]. A characteristic feature of organic inorganic hybrids based on Sb(III)/Bi(III) halides is a rich variety of chemical stoichiometries denoted by a general formula R a M b X 3a+b (where R stands for organic cation, M denotes Sb(III) or Bi(III) and X = Cl, Br, I) which, in turn, leads to many different types of anionic structures. The majority of ferroelectrics crystals crystallize with the RMX 4, R 2 MX 5, R 3 M 2 X 9 and R 5 M 2 X 11 chemical compositions. Among them, a special interest has been focused on the R 3 M 2 X 9 subgroup due to their rich anionic structures: (i) isolated [M 4 X 18 ] 4 groups (zero dimensional anionic layer - 0D) [5], (ii) discrete bioctahedra (0D) [6] (iii) one-dimensional zig-zag chains (1D) [7], (iv) two-dimensional layers (2D) [8]. It should be noted that the ferroelectric properties were found to appear only in the derivatives characterized by 2D anionic layers. Extensive search for new molecular ferroelectrics leads to a group of the halobismuthates(iii) based on the formamidinium cation, e.g. (NH 2 CHNH 2 ) 3 [Bi 2 Cl 9 ] (FBC) and (NH 2 CHNH 2 ) 3 [Bi 2 Br 9 ] (FBB). Notwithstanding the similarity of stoichiometry (R 3 M 2 X 9 -type of compounds), both crystals indicate different type/geometry of inorganic part. In the case of FBC, the anionic sublattice is built up of unique one-dimensional (1D) polyanonic chains composed of distorted [BiCl 6 ] 3- octahedral whereas FBB indicates a honeycomb-like structure (2D-type). In this poster, the structure, thermal and dielectric properties of the FBC and FBB are presented. To throw more light on the molecular mechanism of the phase transitions the 1 H NMR studies were carried out in a wide temperature range. [1] N. Setter, D. Damjanovic, L. Eng, G. Fox, S. Gevorgian, S. Hong and et al., J. Appl. Phys., 100, , (2006). [2] M. T. Chorsi, S. Azizi and F. Bakhtiari-Nejad, Int. J. Mech. Mater. Des. 11, 111 (2015). [3] S. A. Adonin, M. N. Sokolov and V. P. Fedin, Coord. Chem. Rev. 312, 1 (2016). [4] A. Piecha, A. Białońska and R. Jakubas, J. Mater. Chem. 23, 333 (2012). [5] A. Piecha, R. Jakubas, A. Pietraszko, J. Baran, W. Medycki, D. Kruk, J. Solid State Chem. 182, 2949 (2009). [6] H.-Y. Ye, Y. Zhang, D.-W Fu and R.-G Xiong, Angew. Chem., Int. Ed. 53, (2014). [7] H. Ishihara, K. Yamada, T. Okuda and A. Weiss, Bull. Chem. Soc. Jpn. 66, 380 (1993). [8] A. Kallel and J. W. Bats, Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 41, 1022 (1985). 143

146 144 Materials science MECHANICAL PROPERTIES AND MICROSTRUCTURE OF HIGH ENTROPY ALLOY CoCrFeNiMn AFTER HIGH PRESSURE TORSION AT 300 AND 77 K Yu.O. Shapovalov 1, E.D. Tabachnikova 1, A.V. Podolskiy 1, M. Zehetbauer 2, E. Schafler 2, M.A. Tikhonovskiy 3 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 University of Vienna, Boltzmanngasse, 5 A Vienna, Austria 3 National Science Center Kharkov Institute of Physics and Technology NAS of Ukraine, Kharkiv, 61108, Ukraine shapovalov@ilt.kharkov.ua Microhardness HV and the structure of high entropy alloy CoCrFeNiMn subjected to severe plastic deformation (SPD) by high pressure torsion (HPT) at the temperatures of 300 and 77 K and their dependence on exposure time after HPT have been investigated. The initial coarse grain state of the alloy was produced by casting from the melt with the subsequent homogenization of the structure by means of annealing. The alloy achieved is a single phase substitutional solid solution with an average grain size of ~ 4 μm. Torsional strain test for 5 revolutions with the rate 0.2 rev/min was carried out in Bridgman anvils under pressure of 6 GPa at the temperatures of 300 and 77 K. The torque measurements in situ during deformation were produced and the value of torsional shear stress τ in the samples was obtained. The measured microhardness after HPT depended both on the value of torsional strain as on the HPT temperature. The values of shear strain have been calculated by the formula 2 n r / h ; here, n is the number of revolutions, r is the distance from the rotation axis, and h is the sample thickness. The next peculiarities were established: a) increase in stress τ during HPT and in the value of microhardness HV (after HPT) in the nanostructured state as compared with coarse grain (initial) state; b) HV value dependence on γ after HPT at low values of γ due to structure inhomogeneity in the central parts of the disk. The size of the structure inhomogeneity area along the disk radius depends on the HPT temperature and increases with the HPT temperature decrease from 300 to 77 K; c) anomalous decrease in HV values and in τ value along the decrease of HPT temperature from 300 to 77 K, the value HV is independent on exposure time of the samples after HPT. The observed anomalous behaviour of microhardness and torsional shear stress of the alloy CoCrFeNiMn after HPT at 77 K is discussed in the terms of peculiarities of structure appeared during HPT at 77 K such as grain size, dislocation density, formation of new phases induced by HPT.

147 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine DISLOCATION-KINETIC APPROACH TO TENSILE STRESS-STRAIN CURVE CALCULATION FOR PLATE SPECIMENS OF TWO- DIMENTIONAL POLYCRYSTALS OF HIGH PURITY METALS Ye.V. Ftomov Physics Department, V.N.Karazin Kharkiv National University, 4 Svoboda Sq., Kharkiv, Ukraine ftesha@gmail.com The dislocation-kinetic equation of plastic flow is obtained for plate two-dimensional polycrystals of pure metals under uniaxial tension at a constant speed, taking into account the hardening effect of through-the-thickness grain boundaries and the influence of the free surface of the sample as a source and sink of dislocations. Plastic flow of the sample is determined by the kinetics of dislocations which in general might be expressed by an equation that binds the evolution of the dislocation density with the deformation [1, 2, 3]. This approach is based on taking into account the processes responsible for the accumulation and annihilation of dislocations. The current study shows that the dislocation kinetics for plate three-dimensional samples for which most grains are "in-depth grains" with a small amount of "surface grains" is noticeably different from plate two-dimensional samples in which all grains are "surface grains". In the transition from three-dimensional to two-dimensional samples, a size effect arises which must be taken into account. The surface grains form through-the-thickness "vertical" boundaries, which are barriers to dislocations and cause hardening of the sample [4]. All grains of a two-dimensional polycrystal have a free surface which is the source and sink of dislocations. The obtained kinetic equation for plate two-dimensional polycrystals has the following form: ρ (dρ/dγ) = (cos(φ)/ bd s ) ρ + (2/D)(n s /b) + k f ρ 3/2 (sin(φ) / bd) ρ k a ρ 2 where ρ - average dislocation density, γ - shear strain, φ - angle between the slip plane and the tensile axis, b - Burgers vector, d s - average grain size, D - specimen thickness, n s - density of dislocation sources, k f - intensity of dislocation multiplication on forest dislocations, k a - coefficient of annihilation of screw dislocation. The analytical form of tensile stress-strain curves is obtained from the solution of the kinetic equation using the Taylor strain hardening law. The theoretical and experimental data for tensile stress-strain curves for two-dimensional pure aluminum polycrystals with a purity of at.% were compared. It is shown that theoretical and experimental data are in fairly good agreement. [1] U.F. Kocks, H. Mecking, Progr. Mater. Sci, 48, Р (2003). [2] G.A. Malygin, Solid State Physics, V. 35, N. 5, p (1993). [3] G.A. Malygin, V. 35, N. 6, p (1993). [4] P.J. Janssen, T.H. de Keijser, M.G. Geers, Mater. Sci. Eng. A 419, Р (2006). 145

148 146 Materials science NEAR ORDER IN THIN FILMS BY PM-A V.G. Geidarov 1, I.S. Braude 1, N.N. Galtsov 1, N.A. Aksenova 2 1 B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 Ukrainian State University of Railway Transport, Feierbakh Square 7, Kharkiv, 61050, Ukraine geydarov@ilt.kharkov.ua One of the characteristic properties of molecular solids is the ordering of molecules under external influence (temperature, strain, etc.) [1, 2]. In amorphous films, the processes of ordering lead to essential changes in the structural, thermal, and magnetic properties of the material. X-ray diffractometry (XRD) was used to investigate Kapton H polymer films in the basic state, after exposure at liquid nitrogen temperature and after tensile deformation at room temperature. Only diffuse halo is present on diffractograms from all samples. This means, that as a result of deformation and exposure to low temperatures, the samples do not crystallize. Based on the diffraction data, the functions of the radial locations of atoms in the films were constructed. [1] N.N. Galtsov, O.A. Klenova, M.A. Strzhemechny, LTP 28, 365, 2002 [2] L. Jin, C. Bower and O. Zhou, Appl. Phys. Lett., Vol. 73, 1998

149 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 147 Theory of THEORY OF CONDENSED MATTER PHYSICS Condensed Matter Physics

150

151 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine LOW-TEMPERATURE INSTABILITY IN QUANTUM DETECTION OF CHARGE-QUBIT DECOHERENCE BY MEANS OF ONE-DIMENSIONAL TUNNEL JUNCTIONS: EXACT SUMMATION THEOREM FOR REAL-TIME PROPAGATORS G.A. Skorobagatko Institute for Condensed Matter Physics of NAS of Ukraine, 1 Svientsitskii Street, 79011, Lviv, Ukraine gleb.a.skor@gmail.com Presented theoretical study [1] makes progress in our knowledge about the properties of quantum detectors designed on the platform of quantum-point contacts (QPCs) to monitor the realtime decoherence of charge-qubit quantum states. The related area of nanoscience has now a great dynamically growing experimental component (see e.g. Refs.[2,3,6,7]) and plays one among central roles in quantum engineering. In this study the crucial role of the effective dimensionality of QPC electrodes in the processes of charge-qubit decoherence in the procedures of quantum detection has become revealed for the first time. This research exploits a well-developed quantum detector ideology (see e.g. Ref.[4]) and represents a next sufficient step in our understanding of quantum detection physics after the related research on the subject by the author and his colleagues (see Ref.[5]). In contrary to the study of Ref.[5], here (see Ref.[1]) the low- and zero-temperature limit of charge-qubit decoherence due to its quantum detection by means of QPC has been investigated and, moreover, this investigation has been performed by the author beyond the perturbation theory. As the result, it is established for the first time [1] that zero-temperature quantum limit of the detection (i.e. the situation where quantum detector efficiency is maximal and is equal to one) holds only for those QPC detectors having their 1D Luttinger liquid leads with Luttinger liquid correlation parameter g below definite critical value g_cr, which was also estimated [1] as the function of temperature. At the same time, for the QPC quantum detectors with g_cr < g < 1 it has been revealed that their efficiencies tend to zero in the low-temperature limit and this means a breakdown of detection abilities for such types of QPC quantum detectors at sufficiently low temperatures. Moreover, the revealed sharpness of the detector efficiency as the function of Luttinger liquid correlation parameter g in the vicinity of its critical value g_cr at given temperature - clearly signals about the instability of the entire procedure of quantum detection if the latter to be performed by means of QPC quantum detectors with corresponded critical parameters of electron-electron interaction in their leads. All obtained results [1] are exact in the sense, they are based on the exact calculation of qubit decoherence- and detector acquisition of information rates. The latter exact calculation has become possible due to exact mathematical statements: summation (S-) theorem and summation (S-) lemma both being proven for the first time by the author in [1] for the real-time Keldysh contour-ordered propagators with Luttinger liquid tunnel Hamiltonian in the bosonic representation. These exact mathematical statements can represent a separate interest for Luttinger liquid and quantum many-body systems theorists. Also, it is shown [1], that lowtemperature detection instability effect theoretically predicted by the author is able to explain a large and unclear mismatch between expected and observed decoherence timescales in two recent well-known experiments [6,7] on the charge-qubit quantum dynamics. [1] G.A.Skorobagatko, Phys.Rev.B, 98, (2018). [2] G.Cao et al., Nat.Commun., 4, 1401 (2013). [3] D.Kim et al., Nat. Nanotechnol., 10(3), 243 (2015). [4] D.V.Averin and E.V.Sukhorukov, Phys.Rev.Lett., 95, (2005). [5]G.Skorobagatko, A.Bruch, S.V.Kusminskiy, A.Romito, Phys.Rev.B, 95, (2017). [6] J.Gorman, D.G.Hasko, D.A.Williams, Phys.Rev.Lett., 95, (2005). [7] K.D.Petersson, J.R.Petta, H.Lu, A.C.Gossard, Phys.Rev.Lett., 105, (2010). 149

152 150 Theory of Condensed Matter Physics FEATURES OF MAGNETIC ORDERING AND NON-EQUILIBRIUM PROCESSES IN MAGNETICS WITH SPIN S=3/2 AND SU(4) SYMMETRY OF THE EXCHANGE INTERACTION A.V. Glushchenko, M.Y. Kovalevsky Kharkiv Institute of Physics and Technology Academicheskaya, 1, Kharkiv, 61108, Ukraine The study of magnets, whose structural elements have a spin s> 1/2, is a current area of research in modern physics of condensed media [1-3]. In such multiparticle systems, new collective properties of matter and unusual types of magnetic ordering are possible. The objects of experimental studies of these magnetic states are Bose and Fermi gases on optical lattices [4], crystals TmZn, TmCd, CeAg [5]. Based on our developed approach, we considered the dynamics of magnets with spin s=3/2 with the SU(4) exchange interaction. The subalgebras of Poisson brackets of magnetic quantities are studied, for which the exchange interaction has the properties of lower symmetry: SU(3), SU(2)xSU (2), SO(4), SO(5). Nonlinear dynamic equations for such magnetic systems in the Weyl and Cancer bases are formulated. The models of exchange energy are considered, which take into account not only Casimir invariants, which are quadratic in magnetic degrees of freedom, but also of a higher order. On their basis, the question of the equilibrium magnetic state of such systems has been studied. The spectra of collective excitations are calculated and the nature of magnetic anisotropy is clarified for various types of magnetic ordering. The influence of an external magnetic field on the spectra of collective excitations is considered. Comparison of the results obtained with earlier studies on this topic. [1] Zhang S. C., Science, 275(5303), , (1997). [2] Fridman Y. A. et al., Physical review letters, 106(9), , (2011). [3] Kovalevsky, M. Y., Glushchenko, A. V., 349, 55-72, (2014). [4] Buschow K. H. J., Handbook of magnetic materials (Elsevier, V. 15, 2003). [5] Lewenstein M., Sanpera A., Ahufinger V., Ultracold Atoms in Optical Lattices: Simulating quantum many-body systems, (Oxford University Press, 2012).

153 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine NUMERICAL MODELING OF THE DYNAMICS OF PALLADIUM AND NICKEL CLUSTERS AND NANOPARTICLES D.V. Laptev 1, D. Terentyev 2, V.I. Dubinko 3, K. Irwin 4 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 NSC Kharkov Institute of Physics and Technology, Kharkov 61108, Ukraine 3 SCK CEN, Nuclear Materials Science Institute, Boeretang 200, Mol, 2400, Belgium 4 Quantum Gravity Research, Los Angeles, USA laptev.denis.18@gmail.com Palladium (Pd) and Nickel (Ni) are the materials with a strong affinity to hydrogen owing to both their catalytic and hydrogen absorbing properties. In this work Pd and Ni clusters and nanoparticles are considered. Nanoparticles can have a structure that is prohibited in the crystallographic translational-symmetry rules (e.g., the icosahedra(ico) and decahedra (deca) with noncrystalline 5-fold symmetry). Nanoparticles of elements that have a cuboctahedral (CUBO) fcc bulk structure have been observed to have structures with 5-fold symmetry; the most-studied ones include some metallic and rare-gas clusters. As the growth of clusters proceeds beyond a crossover point, a structural transition to the crystalline structures is expected to occur. Experimentally, it has been observed that the structural transitions in clusters are dependent on the sizes of the nanoparticles, as well as the temperature, which demonstrated that the stable structures and transition barriers between metastable structures are both size-dependent. Concerning studies for the transition between crystalline- and noncrystalline-symmetry structures in clusters, previous theoretical studies primarily use classical molecular dynamics (MD) simulations with various empirical interatomic potentials, and the transition is well-known to be dependent on the potentials used. Mackay has proposed a transition model between the 5-fold-symmetry ico and the crystalline structure of fcc cuboctahedra. The ico to fcc transition can be a crucial process near the cross-over point from clusters to the crystalline structure. In this work the metal clusters of Pd and Ni with icosahedral (ICO) and cuboctahedral (CUBO) morphologies as well as their hydrides nanoparticles and bulk lattices have been considered using classical molecular dynamics (MD) and quantum density functional theory (DFT) methods.. The energetic stability of metal clusters of Pd and Ni has been tested by calculation the energy excess of the atoms in the cluster over the energy in the bulk lattice roughly divided by the number of surface atoms. For palladium and nickel clusters with 13, 55 and 147 atoms a structural transformation from cuboctahedral to icosahedral morphology has been observed. It was shown that icosahedral symmetry is more energetically favorable then cuboctahedral. For nickel clusters with 13 and 55 atoms transformation was observed for low temperatures (0.1K), for cluster with 147 atoms transformation began at T=133K, for lower temperatures cuboctahedral Ni147 cluster preserved it`s symmetry and didn t transform to icosahedral cluster. For palladium clusters with 13 atoms JT was observed for low temperatures (0.1K), for clusters with 55 and 147 atoms JT appeared when cluster was heated to high temperatures and after relaxation these clusters became icosahedral. [1] C.M. Wei, C.Cheng, C.M. Chang, J. Phys. Chem. B. 110, (2006). [2] A. L. Mackay, Acta Crystallogr. 15, 916 (1962). [3] A. I. Gusev, Nanomaterials, nanostructures, nanotechnologies, Moscow, 416p [4] V. Dubinko, D. Laptev, D. Terentuev et.al., Comp.Mater.Sci. 158, 389 (2019). 151

154 152 Theory of Condensed Matter Physics TIME OF LANDAU-ZENER-STÜCKELBERG-MAJORANA TRANSITION O.V. Ivakhnenko 1,2,3, S.N. Shevchenko 1,2,3, Franco Nori 3,4 1 B. Verkin Institute for Low Temperature Physics and Engineering, Kharkov 61103, Ukraine 2 V. N. Karazin Kharkov National University, Kharkov 61022, Ukraine 3 Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wakoshi, Saitama , Japan 4 Physics Department, University of Michigan, Ann Arbor, MI , USA olegiv333@gmail.com Landau-Zener-Stückelberg-Majorana (LZSM) transition relates to the tunneling in quantum two-level systems, qubits [1]. Recent interest for studying these transitions and their analogs in different systems is because LZSM transition is one of the basic mechanisms to prepare a qubit in a definite state and drive it. Interestingly, this was studied by the four classics, Landau, Zener, Stückelberg, Majorana, in We recently studied LZSM transitions and their classical analogues in different systems [2]. Now we consider time dynamics of the LZSM transitions and their characteristic time [3]. We compare numerical and analytical solutions for the dynamics of the upper-energy level occupation probability, see Fig. 1. Num P + (t) 0,15 Num P + (t) Num P + (t) Limits P + (t) 0,10 0,05 0, t Fig. 1. Comparison of the numerical solution for the time dynamics of the upper level occupation probability with different transitions times with the same transition probability and with different Δ (size of energy gap) and comparison with analytical (limits) solution. Dashed green line is the boundary of the time for transition for, dotted line is tangential to line with in the point. Δ 0 is defined value of the energy gap size which using for normalization of values. [1] S. N. Shevchenko, S. Ashhab and F. Nori, Phys. Rep., 2010, 492, 1. [2] O. V. Ivakhnenko, S. N. Shevchenko and F. Nori, Sci. Rep., 2018, 8, [3] N. V. Vitanov, «Transition times in the Landau-Zener model», Phys. Rev. A, 1999, 59, 988.

155 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine SLOWING OF ELECTROMAGNETIC PULSES IN THE PROXIMITY OF PHASE TRANSITION TO BOSE-EINSTEIN CONDENSATE IN ULTRACOLD ATOMIC GASES D.M. Raspopova 1, A.G. Sotnikov 2 1 V. N. Karazin Kharkiv National University, 4 Svobody Square, Kharkiv, 61000, Ukraine 2 Akhiezer Institute for Theoretical Physics, NSC KIPT, Kharkiv, 61108, Ukraine raspopova.dariaa@gmail.com We theoretically study the response of ideal gas of alkali-metal atoms to near-resonant electromagnetic perturbation in the region of temperatures close to phase transition to the state with Bose-Einstein condensate (BEC). From the explicit dependencies of the chemical potential on the temperature [1] and developed generalization of the Green s functions formalism [2], we reveal important implications of the BEC transition on the group velocity of laser pulses. A comparison to experimental observations [3] below and above critical temperature is performed. [1] A.G. Sotnikov, K.V. Sereda, and Y.V. Slyusarenko, Low Temp. Phys. 43, 144 (2017). [2] Y. Slyusarenko and A. Sotnikov, Phys. Rev. A 80, (2009). [3] L. V. Hau, S. E. Harris, Z. Dutton, and C. H. Behroozi, Nature 397, 594 (1999). 153

156 154 Theory of Condensed Matter Physics THE INFLUENCE OF COULOMB CORRELATIONS ON MAGNETIC SHUTTLING O.A. Ilinskaya 1, I.V. Krive 1,2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 Physical Department, V. N. Karazin National University, Kharkiv 61077, Ukraine ilinskaya@ilt.kharkov.ua Nanomechanics [1] and nanoelectronics [2] are the two important fields of nanophysics. Nanoelectromechanics [3, 4] and, in particular, electron shuttling [5, 6] are also intensively studied both theoretically and experimentally. Shuttling is a transfer of electrons from a source to a drain electrode by periodically moving quantum dot. Shuttling is possible due to interrelation between tunneling of electrons and the dot vibration degree of freedom. In this work, the influence of electron-electron interaction on the existence of magnetic shuttling is theoretically studied. A typical magnetic shuttle device comprises a movable quantum dot tunnel coupled to magnetic electrodes, held at the same temperature and at different chemical potentials (due to a bias voltage). Magnetic exchange forces act between magnetization of the electrodes and the total electron spin on the dot. These forces crucially depend on the parity of the dot electrons. In the simplest case of one spin-degenerate electron energy level on the dot, the force acts on a singly-occupied dot and equals zero for unoccupied and double-occupied dot. For oppositely magnetized electrodes, held at zero temperature, and in the Coulomb blockade regime, electron shuttling was predicted for values of external magnetic field (oriented perpendicular to the electrodes magnetization) less than certain critical value [7]. Non-zero temperature leads to an effective dissipation implying the appearance of the lower critical magnetic field [8], which borders the small-amplitude vibronic regime and shuttling regime. We study the influence of strength of electron-electron interaction on shuttling in the described model device with oppositely magnetized electrodes, held at finite temperature. We find analytically that for non-interacting electrons, U = 0, there is no shuttling. Our numerical calculations show that there is temperature dependent crossover energy U c (T) between vibronic and shuttling regimes. For U < U c the dot displacement is damped out with time, for U > U c it is amplified until reaches steady-state amplitude. At crossover point, U = U c, the vibrations are maintained at a constant amplitude. The temperature dependence of U c is the main result of our work. This dependence is linear in certain range of temperatures, which agrees with a proposed qualitative picture. [1] M. Poot, H. S. J. van der Zant, Phys. Rep. 511, 273 (2012). [2] S. Andergassen, V. Meden, H. Schoeller, J. Splettstoesser, M. R. Wegewijs, Nanotechnology 21, (2010). [3] M. P. Blencowe, Contemp. Phys. 46, 249 (2005). [4] A. N. Pasupathy, R. C. Bialczak, J. Martinek, J. E. Grose, L. A. K. Donev, P. L. McEuen, and D. C. Ralph, Science 306, 86 (2004). [5] R. I. Shekhter, L. Y. Gorelik, I. V. Krive, M. N. Kiselev, A. V. Parafilo, and M. Jonson, Nanoelectromechanics 1, 1 (2013). [6] A. V. Moskalenko, S. N. Gordeev, O. F. Koentjoro, P. R. Raithby, R. W. French, F. Marken, and S. E. Savel ev, Phys. Rev. B 79, (2009). [7] S. I. Kulinich, L. Y. Gorelik, A. N. Kalinenko, I. V. Krive, R. I. Shekhter, Y. W. Park, and M. Jonson, Phys. Rev. Lett. 112, (2014). [8] O. A. Ilinskaya, S. I. Kulinich, I. V. Krive, R. I. Shekhter, H. C. Park, and M. Jonson, New J. Phys. 20, (2018).

157 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine EFFECTS OF COULOMB INTERACTION AND FRANCK-CONDON BLOCKADE IN TUNNELING OF SPIN-POLARIZED ELECTRONS IN A MOLECULAR TRANSISTOR A.D. Shkop 1, O.M. Bahrova 1, I.V. Krive 1,2 1 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine 2 Department of Theoretical Physics named by academician I.M. Lifshits, V. Karazin National University, 4 Svobody sq., Kharkiv, 61022, Ukraine shkop@ilt.kharkiv.ua In pursuit of optimization of nanodevices and enlarging the area of their application it is interesting to study phenomena where spintronic and Coulomb blockade effects in single molecule transistors (SMT) are in interplay. Our spintronic system consists of two spin-polarized electrodes and a vibrating molecule placed between them. An external magnetic field perpendicular to the plane of leads magnetization is applied. It is well known (see e.g. [1]) that electron-vibron interaction in SMT strongly affects the current in single electron transistors (SET) at low temperatures. External magnetic field, by inducing electron spin-flips, influences current flow of spin polarized electron. For the case when the leads are fully and oppositely (in direction) polarized, external magnetic field plays the role of magnetic gate for spintronic SET. We analyze the influence of magnetic and Coulomb (see e.g. [2]) effects on current-voltage characteristics IV ( ) of single molecule transistors. Using density matrix method, the analytic expression for the average current in terms of density matrix elements were derived in perturbation theory on tunnel level width ( Г / kbt 1). IV ( ) dependence was calculated numerically. The obtained plots demonstrate the following new effects: (i) staged Coulomb blockade lifting in the absence of electron-vibron interaction, (ii) suppression of Franck-Condon steps in the presence of vibronic channels due to Coulomb blockade lifting and (iii) non-monotonic (anomalous) temperature dependence of maximal conductance. The obtained results suggest new functionality of spintronic single electron transistors and they could be significant for engineering of new devices for nanoelectronics and spintronics. [1] J. Koch, F. von Oppen. Phys. Rev. Lett., 94, (2005). [2] L. Y. Gorelik, S. I. Kulinich, R. I. Shekhter, M. Jonson, and V. M. Vinokur, Phys. Rev. Lett. 95, (2005). 155

158 156 Theory of Condensed Matter Physics DYNAMICS IN THE GRAVITATIONAL FIELD OF A TORUS WITH A CENTRAL MASS L.D. Manchenko 1, E.Yu. Bannikova 1,2 1 V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, Ukraine 2 Institute of Radio Astronomy, Ukraine National Academy of Science, 4 Mystetstv Ave., Kharkiv, Ukraine lil.dmitrievna@gmail.com We consider the problem of a test particle motion in gravitational field of a torus with a central mass. It was shown in previous paper [2] that an outer potential of the torus can be represent with good accuracy by the potential of a massive circle (MC) that simplify the particle motion problem in outer torus potential. In such a system there is a circle of unstable equilibrium ("Lagrangian circle") [1]. Stable circular orbits exist only in some region limited by the last possible circular orbit related to the disappearance of the extrema of the effective potential. We call this orbit as "the outermost stable circular orbit" (OSCO) [1] by analogy with the innermost stable circular orbit (ISCO) in the relativistic case of a black hole. In this study we consider the motion of the test particle taking into account a sewing of the outer and of the inner potentials of the torus. In particular the motion of particle near a surface of the torus as well as the possibility to capture the particle by the torus are investigated. We apply these results for the ring galaxies. [1] E. Yu. Bannikova, Monthly Notices of the Royal Astronomical Society, 476, 3269, (2018). [2] E. Yu. Bannikova, V. G. Vakulik and V. M. Shulga, Monthly Notices of the Royal Astronomical Society, 441, 557, (2011).

159 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine ORBITAL ORDERING OF ULTRACOLD FERMIONIC MIXTURES IN OPTICAL LATTICES A.G. Sotnikov Akhiezer Institute for Theoretical Physics, NSC KIPT, Kharkiv, 61108, Ukraine Spontaneous symmetry breaking is one of fascinating physical phenomena, which leads, in particular, to long-range ordered (LRO) phases in solid-state systems. New insights into understanding of complex mechanisms responsible for LRO effects became possible due to trapping of ultracold atoms in optical lattices, where, in particular, antiferromagnetic ordering of two pseudospin fermionic components has been achieved and studied recently [1,2]. Access to orbital degrees of freedom of ultracold atoms in state-dependent optical lattice realized with Yb-173 mixture [3], has provided an extended toolbox for studies of other peculiar phenomena, including ferromagnetism mediated by Hund's coupling [4], Kondo effect, multiorbital polarons [5], orbital-selective metal-insulator transitions, and orbital ordering. In this talk, we report on dynamical mean-field theoretical analysis of emerging lowtemperature phases, which can be achieved in these systems. We show that the four-component Yb- 173 mixture with realistic lattice depths, interaction parameters, and measurements possibilities is a good candidate for studies of antiferro-orbital ordering peculiar to solid-state materials, such as LaMnO3 and KCuF3. [1] A. Mazurenko, C. S. Chiu, G. Ji, M. F. Parsons, M. Kanasz-Nagy, R. Schmidt, F. Grusdt, E. Demler, D. Greif, and M. Greiner, Nature 545, (2017). [2] C. S. Chiu, G. Ji, A. Mazurenko, D. Greif, and M. Greiner, Phys. Rev. Lett. 120, (2018). [3] F. Scazza, C. Hofrichter, M. Höfer, P. C. De Groot, I. Bloch, and S. Fölling, Nature Physics 10, 779 (2014). [4] A. Sotnikov, A. Cichy, and J. Kuneš, Phys. Rev. B 97, (2018). [5] N. Darkwah Oppong, L. Riegger, O. Bettermann, M. Höfer, J. Levinsen, M. M. Parish, I. Bloch, and S. Fölling, arxiv: (2019). 157

160 158 Theory of Condensed Matter Physics PLASMA AND ORDER PARAMETER COLLECTIVE OSCILLATIONS IN GRAPHENE COUNTERFLOW SUPERCONDUCTORS K.V. Germash 1, D.V. Fil 1,2 1 Institute for Single Crystals of NAS of Ukraine, 60 Nauky Ave., Kharkiv, 61072, Ukraine 2 V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv, 61022, Ukraine kvgermash@gmail.com It is known [1] that Cooper pairing results in appearing of specific collective excitations, such as: the Anderson-Bogoliubov (AB) mode (oscillations of the phase of the order parameter), the Schmid (SM) mode (oscillations of the modulus of the order parameter), and the Carlson-Goldman (CG) mode (coupled oscillations of the phase of the order parameter and the scalar potential). These modes can exist under certain conditions. A genuine AB mode can appear in neutral superfluids. The CG mode exists in a very narrow temperature range near TC in dirty superconductors, while in clean superconductors it suffers a strong damping. In this report we consider a possibility of appearing of above modes in so-called counterflow superconductors [2,3]. Counterflow superconductivity can be realized in double layer systems with oppositely charged carriers (electrons and holes) in adjacent layers. In such systems electrons and holes form pairs, which are similar to the Cooper pairs. Collective modes in counterflow superconductors are studied [4] with reference to a double monolayer graphene system. It is shown that the AB and SM modes appear as out-of-phase oscillations of the order parameters of two spin subsystems. These modes are uncoupled from oscillations of the scalar potential. It is established that the AB mode is weakly damped one and its relaxation rate decreases with decreasing of temperature. This mode exists in the frequency domain ω<2δ, where 2Δ is the gap in the electron spectrum caused by the pairing. At small wave vectors q the AB mode has an acoustic dispersion ω qv F / 2 (v F is the Fermi velocity), and its frequency saturates at ω=2δ at large q. The SM mode exists only at small q, it belongs to the frequency domain ω>2δ, and it is strongly damped. The mode associated with the CG mode corresponds to in-phase oscillations of the order parameters of two spin components hybridized with out-of-phase oscillations of the scalar potentials in the layers. It is found that in difference with common superconductors, the CG mode in counterflow superconductors remains weakly damped at all temperatures below T c down to T=0. The CG mode belongs to the frequency domain ω<2δ. Similarly to the AB mode, it demonstrates an acoustic dispersion at small q, and its frequency saturates at =2 at large q. It is also found a strongly damped acoustic plasmon mode in the frequency domain >2. In addition we establish [4,5] the existence of two symmetric (optical) plasmon modes in counterflow superconductors. They correspond to in-phase oscillations of the scalar potentials in the layers. These modes do not couple to order parameter oscillations. [1] I. O. Kulik, Ora Entin-Wohlman, and R. Orbach, J. Low Temp. Phys. 43, 591 (1981). [2] S. I. Shevchenko, Sov. J. Low Temp. Phys. 2, 251 (1976). [3] D. V. Fil and S. I. Shevchenko, LTP 44, 867 (2018). [4] K. V. Germash and D. V. Fil, Phys. Rev. B 99, (2019). [5] K. V. Germash and D. V. Fil, Phys. Rev. B 93, (2016).

161 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine EQUILIBRATION AND THERMALIZATION IN THE PERTURBED 1D XXZ MODEL 159 P. Jaeger 1,2, A. Klümper 2, J. Sirker 1 1 University of Manitoba, Department of Physics and Astronomy, Winnipeg, MB, Canada 2 Bergische Universität Wuppertal, Fachbereich C - Fachgruppe Physik, Wuppertal, Germany jaegerp@myumanitoba.ca The quantum XXZ model is an integrable lattice model, hence exact solutions are available via Bethe ansatz (BA). For many ground-state properties or correlation functions, explicit expressions are available. Expectation values of observables at late times after a quench can be calculated for example using the generalized Gibbs ensemble (GGE) formalism. However, in particular dynamical correlation functions (DCF) are notoriously hard to calculate from BA, and perturbations of the XXZ model can not be treated directly. Using numerics, it is possible both to obtain DCF relatively easy and to include perturbations. When an integrability-breaking perturbation, such as a staggered transversal field or weak disorder is added to the XXZ model, the formation of a prethermalization plateu has been predicted by numerics [1] and was recently observed in an ultra-cold atoms experiment [2]. However, the decay to a thermal state at late times has not been observed so far. Ref. [1] suggests, that in the prethermalization regime, the density matrix of the system is described by a deformed GGE. Using the Quench Action (QA) approach, it is possible to calculate certain DCF for late times exactly from the BA eigenstates by finding a saddle point of the QA functional [3-4]. It is crucial for the QA approach to know both the form factors of the initial state and the relevant excitations around the GGE state at late times. While this strongly limits the cases where analytical solutions are available, this calculation can be repeated with numerically determined eigenstates which provides some insight to the transition from the integrable to the non-integrable case. Prospectively, doing so also elucidates which excitations are relevant for the time evolution. We present numerical data obtained with the light-cone renormalization group (LCRG) algorithm [5], a tdmrg derivate with which we are able to simulate dynamics in an infinitely extended chain. Based on this and exact results, we discuss the decay of DCF at large times in the integrable case and towards the prethermalization plateau when integrability is broken. [1] F. H. L. Essler et al., Phys. Rev. B 89, (2014). [2] T. Langen, T. Gasenzer, J. Schmiedmeyer, J. Stat. Mech (2016). [3] M Brockmann et al., J. Stat. Mech. P12009 (2014). [4] J-S. Caux J. Stat. Mech (2016). [5] T. Enss, J. Sirker, New J. Phys. 14, (2012).

162 160 Theory of Condensed Matter Physics EFFECTS OF FRUSTRATION IN QUANTUM HEISENBERG ANTIFERROMAGNETS ON BILAYER LATTICES V.Ya. Baliha Institute for Condensed Matter Physics of NAS of Ukraine, 1 Svientsitskii Street, Lviv, 79011, Ukraine baliha@icmp.lviv.ua The s = 1/2 antiferromagnetic Heisenberg model on several bilayer lattices (square, honeycomb and triangular) with magnon states from the flat band with lowest energy in the presence of a strong magnetic field is considered [1-4]. Due to the localized nature of the flat-band magnon states, these systems are mapped on the classical lattice gases of hard-core objects. Also, the standard strong-coupling perturbation theory is applied for constructing effective Hamiltonians. These effective models allowed to investigate the phase transitions related to the ordering of localized magnons. These phase transitions belong to the different classes of universality. When completely antiferromagnetic model (square and honeycomb geometry) was considered in full frustration regime, the phase transitions that belong to the universality class of the two-dimensional Ising model were found. In the case of triangular geometry, for a completely antiferromagnetic model, the phase transition belongs to the universality class of the two-dimensional three-state Potts model. When some interactions on the lattice are ferromagnetic the discontinuous phase transition, which at a certain critical point reached the continuous phase transition from the universality class of the two-dimensional Ising model was found. For a completely antiferromagnetic model on a honeycomb bilayer lattice for a small deviations from the full frustration regime, a spin-flop transition, which occurs in a XXZ model with an easy axis of magnetization, was found. On the basis of an effective model, a theory for a magnetic compound Ba2CoSi2O6Cl2 in an external magnetic field for the description of its low-temperature properties is developed. The compound can be described as a quantum spin model on a square bilayer lattice. The results of experiments for this compound have been reproduced and new predictions have been made, which require new experimental studies to confirm them [3]. For completeness of this study, the ground state of the quantum Heisenberg antiferromagnet on the bilayers with different geometries (square, honeycomb) in the absence of magnetic field is investigated. A variational approach has been applied for that. The trial variational wave functions, which describe the state of the system for the certain relations between exchange interaction parameters, are proposed. By comparing the variational energies, the ground-state phase diagrams are constructed. The obtained results are compared with the ones obtained recently by more sophisticated methods. Qualitative consistency and good quantitative agreement for some critical points are observed [5]. [1] T. Krokhmalskii, et al., Phys. Rev. B. 95, (2017). [2] T. Krokhmalskii, et al., Physica B. 536, (2018). [3] J. Richter, et al., Phys. Rev. B. 97, (2018). [4] J. Strečka, et al. Phys. Rev. B. 98, (2018). [5] V. Baliha, J. Richter, and O. Derzhko, Lviv, 2018, Prepr. / NAS of Ukraine. Inst. for Condens. Matter Phys.; ICMP-18-05E.

163 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine CHARGE AND SPIN CORRELATIONS IN LOW-DIMENSIONAL DOPED QUANTUM ANTIFERROMAGNETS Suraka Bhattacharjee 1, Ranjan Chaudhury 2a,b 1,2a SN Bose National Centre for Basic Sciences,Saltlake,Sector-III,Block-JD,Kolkata ,India 2b Ramkrishna Mission Vivekananda Educational and Research Institute,Belur ,India Some of the doped antiferromagnetic insulators show a number of characteristic phases, including high temperature superconductivity at optimal doping concentration. The investigation of spin and charge correlations in the doped phases still remains as a challenging problem in the field of Condensed Matter Physics. In this scenario, we have used a quantum mechanical, nonperturbative approach for determining the charge correlations in terms of generalized charge stiffness constant (spin symmetric) corresponding to the t-j-like models in low dimensions [1]. Our results show a weak dimensional dependence of the variation of effective charge-charge coupling with doping. In the strongly correlated under-doped phase, we have used the nearest neighbour t-j model and projected out all the doubly occupied sites, considering the variational parameter αto be 1 in the Gutzwiller state. Our theoretical results in the under-doped regime in 2D are compared with experimentally extracted effective Coulomb interaction on the layers of La2-xSrxCuO4for low x. Further, in the weakly correlated over-doped regime, we have used three different approaches [1]: (i) t-j model with α=0, for allowing double occupancy on all sites, (ii) t-j model with two higher neighbourhoppings (t1-t2-t3-j model) and α=0 is retained, (iii) lattice analogue of interacting high density electron gas. A detailed comparison is made between results obtained from all these approaches in the various doping regimes. Based on these comparisons we could establish at least the qualitative equivalence of generalized charge stiffness with effective Coulomb interaction in doped antiferromagnetic systems. The fall in charge stiffness with increase in doping does not however change the sign of effective interaction. Thus it can be inferred that superconducting pairing is possible only in the presence of some external attractive interaction. Hence, our results negate the idea of many theoreticians to produce pairing only from the t-j model and clearly indicates that the t-j-like models alone are not adequate for producing pairing in high Tc superconductors. Here, we also present some results of the doping dependence of generalized spin stiffness constant (spin asymmetric) corresponding to the t-j and t1-t2-t3-j models [2-4]. The results highlight a strong dimensional dependence. Furthermore, we have shown that the spin and charge correlations show completely distinct behaviouras functions of doping in the under-doped regime, whereas a very similar trend is seen in the over-doped regime. Similar to charge stiffness, the equivalence of spin stiffness constant and effective exchange constant in the doped phases is also established. [1] Investigation of charge correlations and determination of effective Coulomb interaction in low dimensional doped quantum antiferromagnets, S.Bhattacharjee, R.Chaudhury (2019) [under preparation]. [2] S.Bhattacharjee, R.Chaudhury, Physica B 500, 133 (2016). [3] S.Bhattacharjee, R.Chaudhury, J.LowTemp.Phys. 193, 21 (2018). [4] S.Bhattacharjee, e-poster abstract, 2nd International Conference and Exhibition on Mesoscopic and Condensed Matter Physics, J.Mat.Sc.Eng.,doi: / C1.053 (2016). 161

164 162 Theory of Condensed Matter Physics THE FALICOV-KIMBALL MODEL WITH CORRELATED HOPPING: X-RAY PHOTOEMISSION SPECTROSCOPY D.A. Dobushovskyi Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Street, Lviv, 79011, Ukraine dobushovskiy@icmp.lviv.ua The present study is a continuation of our previous works [1-2] considering the effects of correlated hopping using the Falicov-Kimball model, the simplest model of strongly correlated electrons. Despite its simplicity, the Falicov-Kimball model has a metal-insulator transition for large Coulomb repulsion and is exactly solvable via dynamical mean-field theory in infinite dimensions (or for infinite coordination number for the Bethe lattice). As we found previously for a wide range of the correlated hopping parameters [1], there are some singularities on the singleparticle density of states and on the quasiparticle scattering time (in our interpretation, the last one is similar to the two-particle interference in random media, e.g., weak (anti)localization). Due to these anomalies, there is a huge enhancement on the thermoelectric properties and the optical conductivity exhibits a number of surprising features as well. So the main subject of this work is to study to what extent the anomalous features observed in the DOS and in the transport properties of the Falicov-Kimball model with correlated hopping can be manifested in the X-ray photoemission spectra at finite temperature. [1] D.A. Dobushovskyi, A.M. Shvaika, V. Zlatic, Phys. Rev. B. 95, , (2017). [2] D.A. Dobushovskyi, A.M. Shvaika, Condens. Matter Phys. 21, 2, 23702, (2018).

165 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine COLLECTIVE SCATTERING OF LANGMUIR-GAS STREAM BY IMPURITY CLUSTERS: SHOCK-WAVE ENHANCEMENT BY DISORDER O.V. Kliushnychenko, S.P. Lukyanets Institute of Physics of NAS of Ukraine, 46 Nauky Ave., Kyiv, 03028, Ukraine We show several specific effects of collective scattering for a cloud of heavy impurities exposed to a gas stream. Formation is presented of a common density perturbation and shock waves, both generated collectively by a system of scatterers at sudden application of the streaminducing external driving field [1]. Our results demonstrate that (i) the scattering of gas stream can be essentially amplified, due to nonlinear collective effects, upon fragmentation of a solid obstacle into a cluster of impurities (heterogeneously decomposed obstacle); (ii) a cluster of disordered impurities can produce considerably stronger scattering accompanied by enhanced and accelerated shock wave, as compared to a cluster with regular ordering. We also show that the final steady-state density distribution is formed as a residual perturbation left after the shock front passage. In particular, a kink-like steady distribution profile can be formed as a result of shock front stopping effect. The possibility of the onset of solitary diffusive density-waves, reminiscent of avalanche (or precursor-solitons), is shown. All the results are obtained within the classical two-component Langmuir lattice-gas model [1 3]. Obtained results may be of interest when considering the non-equilibrium (dissipative) structure organization or collective wake formation [2] in an ensemble of impurities, and can find applications in systems with driven hopping transport (e.g., surface kinetics of adsorbed atom, fast ionic conductors, etc.) or serve as a rough model for structure formation in colloidal suspensions [4] or dusty/complex plasmas [5,6]. [1] O. V. Kliushnychenko, S. P. Lukyanets, Phys. Rev. E. 98, (R) (2018). [2] O. V. Kliushnychenko, S. P. Lukyanets, Phys. Rev. E. 95, (2017). [3] O. V. Kliushnychenko, S. P. Lukyanets, JETP 118, 976 (2014). [4] I. Sriram and E. M. Furst, Soft Matter 8, 3335 (2012). [5] J. Bartnick, A. Kaiser, H. Löwen, A. V. Ivlev, J. Chem. Phys. 144, (2016). [6] V. N. Tsytovich, Phys. Usp. 58, 150 (2015). 163

166 164 Theory of Condensed Matter Physics ONE-DIMENSIONAL HEISENBERG ANTIFERROMAGNETS WITH ALMOST LOCALIZED MAGNONS AT HIGH MAGNETIC FIELDS AND LOW TEMPERATURES O.M. Krupnitska Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine, 1 Svientsitskii Street, Lviv, 79011, Ukraine krupnitska@icmp.lviv.ua We investigate the spin-1/2 antiferromagnetic Heisenberg model on one-dimensional frustrated lattices (double-tetrahedral chain [1] and octahedral chain [2]) with almost dispersionless (almost flat) lowest magnon band in the presence of a strong magnetic field. If the band is strictly flat, the thermodynamics of the model can be studied in detail in the low-temperature high-field regime after mapping the problem onto classical hard-core lattice-gas model. Obviously, exact localization of the magnons is not implemented in nature. That is why it is nesessary to determine the behavior of spin models with parameters which almost satisfies the conditions of localization. The main goal of our study is to develop a systematic theory for the low-temperature high-field properties of double-tetrahedral chain and octahedral chain, using the localized magnons approach [3,4]. For this purpose we construct an effective description of one-dimensional chains with triangular and quadrangular traps by means of the localized magnons concept within the strong coupling approximation. The obtained effective models are much simpler than the initial ones: firstly, the effective models have smaller number of sites and secondly, most importantly, they are free of frustration. To analyze the region of the applicability of the obtained effective Hamiltonians we perform extensive exact-diagonalization calculations and compare them with the results for the initial models. We examine the constructed effective models to explain some properties of the frustrated quantum Heisenberg antiferromagnets in the regime of high magnetic fields and low temperatures. [1] M. Maksymenko, O. Derzhko and J. Richter, Acta Physica Polonica A 119, 860 (2011); Eur. Phys. J. B 84, 397 (2011). [2] J. Strečka et al., Phys. Rev. B 95, (2017); Physica B 536, 364 (2018). [3] J. Schulenburg et al., Phys. Rev. Lett. 88, (2002). [4] O. Derzhko, J. Richter, and M. Maksymenko, Int. J. Mod. Phys. B 29, (2015).

167 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 165 TECHNOLOGIES AND Technologies and INSTRUMENTATION Instrumentation FOR PHYSICAL EXPERIMENTS for Physical Experiments

168

169 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine SCANNING METHOD FOR DETERMINING THE QUALITY OF THE LENS SURFACE O.O. Fomin Kharkiv National University of Radio Electronics, 14 Nauky Ave., Kharkiv, 61166, Ukraine The method of noncontact research of quality of lenses is in-process investigated. This method is actual on the stage of planning or making single prototypes of aspheric lenses. A method consists in what to form great number of rays parallel to the optical axis of the investigated lens. Through an automatic co-ordinate table the initial coordinates of outgoing ray are set. Registration of vector of the refracted ray takes place through two screens. A ray on these screens gets through a beam-splitting plate. Distances from an entrance window to the screens are different. The difference of motion of ray makes minimum 10мм A light-spot registers oneself through two chambers. On the pictures of spot from chambers determine the coordinates of touch of ray with screens. On the got coordinates of two points through that a ray resembles we restore the vector of the refracted ray. On the base of vector of the incoming ray refracted and it is possible to define the coordinates of transit of two environments point. Lining up the great number of points of refractions of ray it is possible to get the coordinates of surface of lens. This method is applicable at planning of aspheric lenses. Experimental device has been created for the experiment. We used a laser with a wavelength λ=532nm. The device has limitations for measuring radii of curvature above 100mm. Scanning step is ½ beam diameter. The accuracy of the calculation of the point coordinates is 0.1 mm. As a result of scan-out we get a coordinate scale, that must be confronted with the computer model of lens, and if necessary bring in adjustment in technology of production. This method allows to save time and money on the stage of planning of aspheric lenses. 167

170 168 Technologies and instrumentation for physical experiments LONG-WAVELENGTH INFRARED CRYOGENIC FILTERS P.V. Kiporenko 1, A.P. Ovcharenko 1, Duong Thi Nhu Tranh 1,2, N.L. Dyakonenko 3, E.Yu. Gordiyenko 4, Yu.V. Fomenko 4 1 V.N. Karazin Kharkov National University, Svobody sq., 4, Kharkov, 61022, Ukraine 2 Hochiminh city university of technology, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City (7000) 3 National Technical University Kharkiv Polytechnical Institute, 2 Kyrpychova str.,61002, Kharkiv,Ukraine 4 B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Nauky Ave., Kharkiv, 61103, Ukraine yufomenko@ilt.kharkov.ua Calculation and fabrication of a set of cooled to liquid nitrogen temperatures long-wavelength IR filters with a specified spectral characteristic have been performed. Such filters are placed in thermal imaging systems directly in front of a cooled photodetector operating in backgroundlimiting mode. In this case, the limitation of the spectral range of the incident radiation leads to an increase in the photodetector detectivity by reducing the parasitic and background radiation The synthesis of the filters was carried out by a method combining analytical and numerical approaches. Novel original formulas for the side extremum envelopes have been used. The basis of the filter design was a package of alternating quarter-wave films with high and low refractive indices. This package was framed on both sides by a set of layers of the similar materials to correct the optical characteristics of the entire system. The synthesis process was to find the number and optical thickness of the corrective film layers. The difficulty was the disparities between the cryogenic temperature of the filter utilization, and high temperature the layer deposition, that leads to a significant change in the refractive indices of the layers. Therefore, the synthesis itself was carried out for low temperatures, and then the optical characteristics and layer thicknesses were recalculated for the coating deposition temperature. The literature data of temperature dependences of the layer and substrate refractive indices were used in the calculations but prior to filters fabrication, refractive indices were refined in according to experimentally measured values of the each refractive index of deposited individual layer. In accordance with the calculated layer thicknesses and sequence, the films were deposited on both sides of the substrate by RF magnetron sputtering using ZnS and PbTe targets. Discs with a diameter of 8 mm and a thickness of 0.5 mm of crystalline Ge were used as substrates. For the experimental measurement of the transmission spectra of the fabricated filters, a thermal imager based on a HTSC bolometer has been used [1]. Using a set of 20 IR dispersive filters, each with a bandwidth of 1 μm, the spectral dependence of the bolometer response to blackbody radiation was measured both with and without the each filter placed in front of the detector. The measured spectrum of the transmittance of the fabricated filters corresponded to the calculated one within the limits of the permissible error. [1] E. Yu. Gordiyenko, G. V. Shustakova, Yu. V. Fomenko, and N. I. Glushchuk, Instruments and Experimental Techniques. 56 (4), 485 (2013) [PTE, No. 4, 125 (2013)].

171 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 169 ARTIFICIAL NEURAL NETWORK AS AN INSTRUMENT FOR THE COMPLEX RELAXATION SPECTRA DECOMPOSITION I.V. Lishchuk, V.V. Ilchenko, V.Y. Opylat, S.V. Tyshchenko Institute of High Technologies, Taras Shevchenko National University of Kyiv, 03022, Hlushkov av. 4g, Kyiv, Ukraine The research, described in this work, are stimulated by the applied problem development of reliable algorithms for analysis of the complex relaxation spectra with exponential components and noises, which are comparable with the signal amplitude. Results of this research will become a part of software package for DLTS (Deep Level Transient Spectroscopy) equipment the authors are currently working on. Improvements of the classic Lang method [1] are made in a several ways by applying different measurement and data acquisition techniques [2], and by development of the data processing algorithms [3]. As for the last part, along with the classical processing methods digital Wavelet pre-filtration and statistic-based exponential approximation are used. Current work is an attempt to complement mentioned algorithms with an artificial neural networks (ANN). The applicability of ANN to this kind of problems has been proven in [4]. Despite that, the optimization of network topology, training algorithm are still an open questions. The fully connected multilayer perceptron has been chosen as a basic architecture. Two problems has been considered classification problem in form of defining of the exponential components number in the measured signal, and regression problem in form of defining of the amplitude and decay times values. The input signal has been modelled as a sum of exponents with the addition of Gaussian noise. ANN are trained by supervised learning method the target parameters are know due to accordance with ones, generated for direct problem. Train set contains samples and validation set 1000 samples, and provides a compromise between the time consumption and training quality. Testing results shows, that current ANN architecture with five layers makes possible to recognize the number of exponential components (considering τ 1 /τ 2 > 1.2) and the values C and τ of single-exponent signals with relative error ~0.02%. The numerical analysis of the multi-exponent signals requires further improvement of networks architecture and its training algorithm. Despite that, the current ANN are also applicable to the statistic-based analysis algorithm, the efficiency of which depends on knowing of the component number. The high stability to noises level has been shown in [3, 4]. [1] D. V. Lang. J. Appl. Phys. Vol.45, No. 7, (1974). [2] O. V. Tretyak, V. J. Opylat, Y. V. Boiko, D. B. Gryaznov, I. A. Derkach and V. Yu. Povarchuk. Sensor Electronics and Microsystem Technologies, 1, (2010). [3] S. V. Tyshchenko, I. V. Lishchuk and V. J. Opylat. Applied Physics and Engineering (YSF), 2016 II International Young Scientists Forum, IEEE Conference Publications, DOI: /YSF , (2016). [4] D. B. Gryaznov, S. A. Korin, V. J. Opylat and O. V. Tretyak. Sensor Electronics and Мicrosystem Technologies T.3 (9), 4, (2012).

172 170 Technologies and instrumentation for physical experiments ROBOT ASSISTED FABRICATION TECHNIQUES OF 2D HETEROSTRUCTURES Divya Jyoti 1, Digvijay Singh 2 1 Department of Atomic Physics, Eotvos Lorand University 1117 Budapest, Pazmany Peter Setany 1, Hungary 2 J.C. Bose University of Science and Technology, YMCA Mathura Rd, Sector 6, Faridabad, Haryana , India alicedivya.tomar@gmail.com Fabricating 2D heterostructures manually in a clean room is a gruelling process. It involves lot of human effort and involvement. To reduce the pain, some of us have come up with the idea of robot assisted techniques. These robots are designed such that they can perform jobs like exfoliation of crystals on silicon chips, chip handling, flakes sorting and their stacking. It uses image processing and contrast play to distinguish desired flakes for stacking. Basically the apparatus contains twin robots which handles the task at 2 stations, namely exfoliation and stacking stage. The exfoliation worker robot is designed to handle blue tapes (used for manual exfoliation) and fold them multiple times to cleave the crystal layers. Later, it presses the tape down to the bottom silicon chip with an accurately observed firm press. An Image processing pipeline is constructed to sort out useful crystal flakes. This pipeline utilizes entropy threshold value of the gray scale image and creates a plot of the region under observation. By advanced selection mechanism and a required human confirmation, the process is pushed forward. A similar stack worker robot holds the glass slide and is caliberated to handle the z-axis movement and intelligent heating mechanism. An additional feature is its rotation and tilt stage ability which is robot handled and is programmed to process as per user s demand. The main advantage of this technique is its accuracy and possibility to be used in a glove box. Also, multiple chosen flakes per chip can now be used which were lost in manual techniques. Our working prototype s ability and compatibility will be discussed and some more features will be highlighted in this paper. [1] S. Masubuchi and M. Morimoto, Autonomous robotic searching and assembly of twodimensional crystals to build van der Waals superlattices (Nature Commun., 2018). [2] Riccardo Frisenda and Andres Castellanos- Gomez, Robotic assembly of artificial nanomaterials (Nature Nanotechnol., 2018).

173 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine AUTOMATION SYSTEM FOR SEMICONDUCTOR DEVICES PARAMETERS MEASUREMENT 171 R.V. Zaitsev, M.V. Kirichenko, D.S. Prokopenko, M.G. Khrypunov K.A. Minakova, G.A. Drozdova National Technical University «Kharkiv Polytechnic Institute» 2 Kyrpycheva St., Kharkiv, 61002, Ukraine zaitsev.poman@gmail.com The basic method of semiconductor devices parameters determination is current-voltage characteristics (CVC) measurement and analytical processing. The existing measurement systems for realization of this method are expensive and complex, what makes them economically unprofitable in terms of Ukrainian production. Taking into account the expounded information, we proposed to constructively perform a measuring complex in a prefix to a PC form. It consists of two functional blocks: a control and a measuring one. The control unit provides the conversion of the digital control signal coming from the PC into the analog form with its further supply to the actuating elements to create the required physical conditions for carrying out the experiment. In the measuring unit at the hardware level, the principles of measuring the physical parameters of the test sample have been realized. For example, it could be current and voltage and their subsequent digitization for further transfer to the PC. The exchange of digital information with installed on the PC the management and data processing program is performed with connecting the control and measuring units to the PC via a standard USB hub. The constructive control unit is based on the Atmel ATMega32 serial microcontroller with the firmware similar to the "framework" program type to provide complete control over the processes from the control and data processing program on the PC. The microcontroller is connected consistently (in series) with a 10-bit digital-to-analog converter Analog Devices AD7533, the necessary operational amplifiers, for example, Texas Instruments LM358 and the output keys of the BD238 and BD237 types. This sequence allows to set the voltage in the range of ± 12V at a current of up to 1A with a minimum step of about 5 mv on the output of the unit. It is quite enough for carrying out research on the CVC of a wide range of the solar cell and semiconductor devices of the various designs. In order to avoid introducing an additional error it was decided to make the measuring unit on the basis of the calibrated measuring devices manufactured industrially (for example of the Mastech MS8040 type), which have a digital output via the RS232C interface. These devices can perform the voltage and current metering device functions during measuring the CVC of the solar cell. The UART-USB converters connected to them provide for the conversion of the digital signals into a form necessary for further transfer to a PC via the USB interface. According to the above-described constructive solutions, the measuring complex sample for carrying out the CVC was made. To control the processing and storage the results process, a control program was developed and written in C#.Net. The manufactured sample of the measuring complex approbation was carried out with measuring the current-voltage characteristics of the electronic equipment key elements, such as resistors, diodes and solar cells and their subsequent comparison with the CVC measured with the classical instruments: a characteristic tracer, an oscilloscope, DC bridges etc. Thus, it can be concluded that the proposed economical CVC measurement system is capable to provide rapid and economical certification of wide electronic device range, in particular solar cells, with a sufficiently high accuracy. An average measurement error does not exceed 1% by measuring and subsequent analytical research CVC of the studying devices. At the same time, the estimated cost of such a complex does not exceed $ 200, what will allow it to be widely used in conjunction with a PC at all workers and research sites that require intermediate and final monitoring of semiconductor devices.

174

175 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 173 AUTHOR INDEX A Akimov V Aksenova N.A Andrievskii V Apostolov S.S , 83 B Babkin R.Yu Bagatskii M.I Bahrova O.M Baldycheva A Baliha V.Ya Bannikova E.Yu Barabashko M.S Barke I Basnukaeva R.M , 111, 138 Batyuk L.V Bedarev V.A Begun E Beliayev E.Yu Berkutov I Bevz V.M Bezuglyj A.I Bhattacharjee Suraka Bialas P Bilych I.V Birchenko А.P Bludov A Bludov M.A Blyznyuk A.V Boldyrev K.N , 67 Bondar I.S Bondarenko P.V , 70 Bondarenko S.I , 59, 118 Boryak O.A Braude I.S Bunyaev S.A C Cermak J Chagovets T.V Chagovets V.K Chaika M Chaudhury Ranjan Cherednychenko S Chikhradze M D Dalakova N.V Delmonte D Demediuk R Desnenko V.A Dobrovolskiy O.V , 54, 59, 75 Dobushovskyi D.A Dolbin A.V , 111, 138 Dolhopolova D.A Doronin Yu.S Drozdova G.A Dubchak T Dubinko V.I , 151 Duque C.A Dyakonenko N.L Dzebisashvili D.M Dzhenzherov O.S E Eselson V.B , 111 Ezerskaya E.V F Fedorchenko A.V Feigel'man M.V , 53 Fenchenko V.N Feodosyev S.B , 117 Fertman E.L Fil D.V Fil V.D Fomenko L.S Fomenko Yu.V Fomin O.O Fomina O Frolov V.A Ftomov Ye.V Fysun Ya.Yu G Galtsov N.N , 146 Gamayunova N.V Gauzzi A Gavrilko V.G , 111 Geidarov V.G Germash K.V Gilioli E Glamazda A.Yu Glushchenko A.V Golub V.O Goncharenko A Gordiyenko E.Yu Gospodarev I.A , 117 Grechnev G.E... 29, 50 Gritsay D.O Gruszecki P Gudim I.A , 74 Gudimenko V.A Guslienko K.Yu Gutowska M.U , 71 H Harbuz D.O Hejtmanek J Herus A.O Holub M.E Horielyi V.A Hreb V.M Hubenko K.A Hübner U , 59 Hurova D.E

176 174 Huth M , 59, 75 I Il ichev E.V , 59 Ilchenko V.V Illinskaya O.A Illyashenko L.N Irwin K Ivakhnenko O.V Ivanov B.A J Jaeger P Janikashvili G Jeżowski A K Kakazei G.N Kalchenko A.S Kaman O , 69 Kamarchuk G.V , 106 Kamchatnaya S.N Kamenskii D.L Kapuza S.S Karachevtsev M.V , 126 Karachevtsev V.A , 126 Karachevtseva A.V Karaseva E.V Karpov D.S Kavok N Khaimovich P.A , 142 Khalyavin D.D Kharchenko A.Yu Kharchenko Yu.M Kharlan Y.I Khlistuck M.V , 111 Khlistyuck M.V Khrustalyov V Khrypunov M.G Khyzhniy I.V Kiporenko P.V Kirichenko M.V Kizilova N.N Klimin S.A Kliushnychenko O.V Klochkov V Klümper A Kobets M.I , 71 Kobzar I.P Kolodiy I Kolodyazhnaya M.P Komarov K.K Konotop A.P Konstantinov A.M Konstantinov V.A Kosevich M.V Kotov Ya Kotvitskaya L.A Kovalevsky M.Y Koverya V.P , 59, 118 Kral L Kravchuk O Kravtsov V.E Krawczyk M Krevsun A.V , 59 Krive I.V , 155 Kruglov S Krupnitska O.M Kuličková J Kurnosov N.V Kutko K.V Kuzmin N.N Kuznetsov V.L Kvitka N Kvitnitskaya O.E L Lange R Laptev D.V Laroze D Lemmens P Len T Leonov V.O Leonyuk N.I Levenets A.V Lishchuk I.L Listkowski A Litvinov Yu.V Lochbrunner S López-Mariscal C Lopushenko I.V Lubenets S.V Łuczka J Lukienko I.M Lukyanets S.P Lupascu D.C Lyakhno V.Yu Lykah V.A , 134 Lyogenkaya A.A M Maidanov V.A Maizelis Z.A Makarov N.M Maksimchuk P Mal tsev V.V Malkin B.Z Malyukin Y.V Manchenko L.D Marinin O Mataradze E Mats A.V Matzui L Mazanov M.V Meglinski I Meleshko V.V , 118 Merenkov D.N Mezzadri F Mielnik N Mikhin N.P Minakova K.A , 171 Mirzoiev I Morozova O.M Moseenkov S.I Moskalenko V.A Mykhailenko Kh Mysko-Krutik N N Naidyuk Yu.G Nakonechnyi M.A Navas D

177 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 175 Neoneta A.S Nerukh O.G Nesterenko N.M Nori Franco O Okovit V.S Olekhnovich N.M Omelchenko L.V Opylat V.Y Ostapovets A Ovcharenko A.P Ovsiienko I P Panfilov A.S Pashchenko M , 69 Pashchenko V.O , 65 Pashkevich Yu.G Petrenko E.V Petrov E.G Pistunova K Plokhotnichenko A.M Poboiko I Podolskiy A.V Pokhila A.S Pokutnyi S.I Pond R.C Ponomarev A.N Poperezhai S.N , 85 Popova M.N... 49, 67 Pospelov А.P , 106 Prokhvatilov A.I , 118 Prokopenko D.S Pushkarev A.V R Radyush Yu.V Ramanauskas R Raspopova D.M Revyakin V.P Rokhmanova T Ropakova I.Yu Rubets S.P Rusakova H.V Rybalko O.S Ryzhov A.I Ryzhova O.A S Sachser R , 59, 75 Sagan V.V Salak A.N , 80 Salamon S Saliuk O.Y Saltykov D.I Savchenko E.V Savchuk E.S Savina Yu Savitsky V Savytskyi A.V Schafler E Sedykh D.S Serra A Shapovalov Yu.O Sheshin G Shevchenko S.I Shevchenko S.N Shevchenko S.N , 62 Shevchenko Ye.V Shklovskij V.A Shkop A.D Shkurdoda Yu.O Shmat'ko A.A Shnyrkov V.I Shpylka D Shulgin N.A Shumeiko V.S Shvartsman V.V Sirenko V.A Sirker J Sivakov A.G Skorobagatko G.A Slyusarenko Yu.V Smolianets R.V Sokolenko V.I , 141 Solodovnik A Solovjov A.L Soroka А.А Sorokin V.A Sorokin А.V Sotnikov A.G Sotnikov A.G Speller S Spiechowicz J Stanulis A Stepanian S.G Stognii N.P Strek W Sumarokov V.V Sushenko D Syrkin E.S , 117, 134 Syvolozhskyi O Szewczyk A , 71 Szewczyk D , 108 T Tabachnikova E.D Tarabara U.T Taran A.S Tartakovskaya E.V Tavlalashvili K Terekhov A.V , 56 Terentyev D Tikhonovskij M.A , 142, 144 Tiutiunnyk A Tomala R Tranh Duong Thi Nhu Trotskiy E.N Trusova V.M Tulupenko V Turutanov O.G Tyshchenko S.V U Usenko E.L Uyutnov S.A V Vaisburd A.I Vakula A

178 176 Vakula V.L Valeev V.A Vasylechko L.O Vatazhuk O.M Verseils M Veverka P , 69 Vieira D.E.L Vinnikov N.A , 111, 138 Volkov S.N Vovk N.R Vovk O.M Vovk R.V , 60 Vrakina V.A Vus K.O W Waluk J Wende H Wolter S Wulferding D Y Yampol skii V.A , 83 Yavetskiy R.P Yedelkina Ye.V Yefimova S.L , 113 Z Zabrodin P.A Zaitsev R.V Zajarniuk T , 71 Zdorevskyi O.O Zehetbauer M Zhekov K.R Zinoviev P.V Zloshchastiev K.G Zobnina V.G Zoryansky V.N Zvyagin A.A Zvyagina G.A Zyman Z

179 X International Conference for Professionals & Young Scientists LTP June 2019, Kharkiv, Ukraine 177 Scientific Edition X International Conference for Professionals & Young Scientists LOW TEMPERATURE PHYSICS ICPYS LTP 2019 in memory of B.Verkin for his 100th birthday anniversary Conference Program & Book of Abstracts Підписано до друку р. Формат 60х90/16. Папір офсетний. Гарнітура «Times New Roman». Друк лазерний. Наклад 156 прим. Видавець: ФОП Панов А.М. Свідоцтво серії ДК 4847 від р. Надруковано в типографії ТОВ «Цифрова типографія» м. Харків, вул. Данилевського, 30.

180