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Information × Registration Number 0212U001477, 0109U001358 , R & D reports Title Spin dynamics, phase transitions, мagnetoelastic effects in the мagnetics popup.stage_title Head Berzhansky Vladimir Naumovich, Registration Date 07-02-2012 Organization National Taurida V. Vernadsky University popup.description2 Report on SRA: 199 p., 57 fig., 2 tables, 209 sources. The object of research is spin dynamics in spin nematics, strongly nonlinear magnetoacoustic materials, amorphous microwires, triple magnetic semiconductors. The aim of researh - to investigate theoretically and experimentally the spin dynamics in spin nematics, strongly nonlinear magnetoacoustic crystals, and amorphous magnetic microwires in the conditions of giant magnetic impedance, and also in triple magnetic semiconductors under the conditions of NMR. Research methods: the method of spin coherent states, Green functions diagram technique, nuclear magnetic resonance, magnetoacoustic parametric resonance, MW reflectometry. Results and their novelty. For the first time the theory of spin dynamics is built for the new class of materials that possess the quadrupole parameter of order - the spin nematics. The dependencies of giant magnetic impedance in amorphous magnetic microwires are determined under the influence of different configurations of elastic tensions and static magnetic fields. For the first time in the wide range of temperatures the parametric quasiphonon triades coupling is demonstrated in single-crystals with giant magnetoelastic interaction. In the supercritical mode the process possesses explosive dynamics that is adequately described by the nonlinear theory developed in the work. With the help of NMR method, it is shown that in compositions with the metallic type of conductivity in the system of triple magnetic semiconductors of CuxFe1-xCr2S4 with a concentration phase transition a metal-semiconductor compensation of valence of ions of Cu+ goes due to the change of quantitative correlation of ions of Cr4+ and Сr3+, and in compositions with semiconductor conductivity due to the ions of Fe2+ and Fe3+. Scientific research work was executed in co-operation with the French partners from the institute of electronics, microelectronics and nanotechnologies (Lille, France) and partly supported by two grants of DFFD of Ukraine within the program of two-way Ukrainian-French collaboration and embassy of France "Doctorant Cotutelle". Research represents a substantial contribution to development of fundamental understandings in physics of magnetic semiconductors. The work was executed within the framework of priority direction of development of science and technique in Ukraine "New substances and materials". The results are planned to be used for development of new generation of ultrasonic scanners and creation of new materials for spintronics. SPIN NEMATICS, NMR, GIANT MAGNETIC IMPEDANCE, MAGNETIC MICROWIRES, PARAMETRIC INSTABILITY, NONLINEAR MAGNETOACOUSTIC CRYSTALS Product Description popup.authors Євстаф'єв Олександр Іванович Бержанський Володимир Наумович Бутрим Володимир Іванович Власова Тетяна Августівна Горбованов Олександр Іванович Кузнєцов Андрій Сергійович Лагунов Игор Михайлович Ляшко Наталія Василівна Полулях Сергій Миколайович Пономаренко Володимир Іванович Попов В'ячеслав Валерійович Потапова Олена Володимирівна popup.nrat_date 2020-04-02 Close