Prof. Georgiy Levchenko
Jilin University, China
Title: Pressure effect on the spin-transition properties of the metalloorganic compounds and spin crossover phenomenon in future spintronics
Abstract:
Molecular magnetism, coordination compounds and spin crossover (SCO) phenomenon are the perspective phenomena and materials for future chemistry and physics. The spin transition (ST) phenomenon is the most spectacular property among them because the spin state of magnetic ions in these compounds regulates most their properties.
The spin state depends on the value and symmetry of the crystal field; therefore, the pressure that directly changes the value of the crystal field along with the temperature is a beneficial external stimulus for inducing the spin transition and controlling its behavior. The parallel use of chemical methods for the synthesis of new materials and pressure has made it possible to deeply study the nature of this phenomenon and describe it on the thermodynamic and microscopic levels, as well as along with traditional areas of possible use, such as: color imaging; recording and storage of the information at the molecular level; various sensors and switches, get direct use areas such as barocaloric, thermochromism and baro-chromism.
The report consists of the short excursus in the nature of the spin transition phenomenon, and the describing of the spin transition influence on structure, magnetic, optical and vibration properties of the SCO materials as well as the control of them by pressure. The synthesis of new materials by replacing ligands and changing of the structure and dimension of compounds also in line of report. Attention will also be paid to possible ways of spintronics development based not only on the spin of electrons, but also on the spin of ions. A special attention will be payed on the prospects for the development of barocaloric and baro-chromic effects of spin-crossover materials. The expanding synthesis of new organometallic materials, the development of physical research methods and the increase in the sensitivity of modern instruments make it possible to significantly expand the fields of application of the spincrossover phenomenon and molecular magnetism.
Biography:
Prof. Georgiy Levchenko graduated the Physic Department of the Donetsk National University, Donetsk, Ukraine and received diploma of the radiophysics in 1974. In 1984 he graduated post graduate courses of the Donetsk Institute of Physics and Engineering named after Galkin A.A. receiving the degree of Candidate of science (PhD). The title of the thesis is “The influence of High Pressure on the Parameters of Spin- Hamiltonian of NiSiF6*6H2O” In 1994 he obtained the degree of Doctor of science. The title of the thesis is “Thermodynamic Properties of Systems with Weak Spin-Spin Interactions”. In 2011 he received the title of Professor of Solid-state physics in National Academy of Science of Ukraine (NANU). In 2015 he has been nominated as Corresponded Academician of the NANU. In 2017 he obtained the project from the program 1000 talents of China and from this date he is Professor of the Jilin University. His scientific interests are Solid State physics, Magnetism, Molecular magnetism, Spin crossover phenomenon and compounds, nanomaterials, vibrational molecular relaxation. Starting from 1996 he closely cooperates with chemists: the group of Prof. P. Gutlich, University of Mainz, Germany; group Prof. E. Coronado and the group of Prof. J. Real, University of Valencia, Spain, as well as with a group of young chemists from Taras Shevchenko University, Ukraine in the field of research of coordination materials, spin transition phenomenon and influence of spin states on the variety of properties of spincrossover materials. In result of this collaboration it has been synthesized a row of new spin crossover compounds, studied their physical properties and developed the thermodynamic and microscopic theories. During his work, he published more than 250 papers in the world's leading journals, wrote one monography and developed a number of high-pressure chambers and other equipment for the study of magnetic, optical and Mossbauer properties in a wide range of temperature and pressure.