State Key Laboratory of Superhard Materials and International Centre of Future Science of Jilin University, China

Biography: Georgiy Levchenko is a Professor of State Key Laboratory of Superhard Materials and International Centre of Future Science of Jilin University, China. He also is affiliated with Donetsk Institute of Physics and Engineering of National Academy of Science of Ukraine as Head of Physics of Phase Transformations Department. He collaborates with many scientific groups of Europe and America. He is a winner of the Shubnikov Prize (2013) and Correspondent member of the National Academy of Science of Ukraine. His fields of interests are material science; molecular materials; Superhard materials; Solid state physics; pressure, structure, magnetic, resistive and optical experiments. His works in the field of pressure influence on magnetic and optical properties of molecular magnets are widely known in the molecular science.

Speech Title: Spin Transition as Direction in a Modern Spintronics and its Electrical Voltage Control at Room Temperature

Abstract: The progress in IT technologies requires new materials and controlling methods of their properties. For decreasing the sizes of memory devices, the exploring of the memory units on molecular scale using spincrossover phenomenon is proposed now. Over the past few years, a number of organic-inorganic metal coordination compounds with the carbon-nitrogen ligand environment of a bivalent iron ion and with a spin transition temperature close to room temperature have been synthesized. The transition temperature of these compounds moves to room temperature when pressure is applied to the samples. A very interesting compound of {Fe(pz)[Pt(CN)4]} was also obtained which has a room transition temperature. In this regard, in order to be able to use this phenomenon in practice, it becomes necessary to have convenient methods for controlling the spin transition and its registration. The presentation briefly describes the state of affairs in obtaining new spin-crossover materials and the study of spin transitions in them using external influences, and also presents a new fine method of controlling the spin transition at room temperature using electrical voltage. The pressure induced spin state switching is steadily driven through a piezoelectric ceramic element. The change of the spin state induced by pressure is easily monitored through changes in the optical spectra of the compound. After calibrating the spin state change with voltage and pressure variations we have received the sensitive pressure sensor. The results demonstrate that {Fe(pz)[Pt (CN)4]} responds to as small pressure variations as 0.001 GPa (10 atmospheres), thereby probing its efficacy to work as an effective pressure sensor. To the best of our knowledge it is the first time that an electrical voltage is used to induce a spin state switching driven by pressure in a metal coordination compounds.

Keywords: Spin transition, pressure, electrical voltage, spintronics