| Andrey V. Prosvirin |
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General Information
Title: Doctor of Physics Address: Kazan Physical-Technical Institute Russian Academy of Sciences Sibirsky Tract str., 10 420029 Kazan, Russia Phone: 007-8432-387370 Fax: +7-8432-765075 E-mail: prosvirin@mail.knc.ru, prosvirin@narod.ru URL: http://prosvirin.narod.ru Research Area: Condensed Matter Physics Education: 1997, Ph.D. in Physics of magnetic phenomena, Kazan Physical-Technical Institute, Russia 1990, M.Sc. in solid state physics, Kazan state University, Russia, Specific Topics Condensed matter is an immensely broad field that encompasses matter in forms ranging from foams, two-dimensional films, mesoscopic clusters and porous media to amorphous solids, polymers, liquid crystals, and single crystals of conventional materials such as silicon or iron. My research has involved a number of areas of condensed matter physics, including liquid crystals, magnetic materials, metallocomplexes, magnetooptics, birefringence phenomen. The current focus within the investigation of magnetic properties and molecular organisation of novel liquid crystals possessing of large magnetic anisotropy. Metallomesogens, or metal-containing liquid crystals are a new class of materials with some unusual (for conventional liquid crystals) physical properties, such as paramagnetism, large magnetic anisotropy, and one-dimensional conductivity. Most of the known liquid crystals are diamagnetics with a small magnetic anisotropy, and even paramagnetic liquid crystals containing transition group elements, have insufficiently large magnetic anisotropy. My interest in condensed matter experiments extend from fundamental studies of phase transitions to applied physics and materials science. Recently, my work has focused on investigation of mesophase orientation and magnetic exchange using temperature dependence of magnetic susceptibility. In addition, I do calculations of magnetic anisotropy. The alignment of liquid crystals by magnetic fields offers some advantages, with respectto the alignment by electric fields. The absence of conductive elements in devices gives the possibility to use a wider class of compounds since electrochemical reactions are no longer in play and requirements on stability of substances are therefore droped. Application of magnetic field produces no electrohydrodynamic effects which could destroy orientation of liquid crystal materials. The magnetic fields make it possible to obtain a broad variety of molecular orientation. Overcoming requirements to the magnitudes of external electric and magnetic fields capable of producing a substantial response in a liquid-crystalline system is of great interest in electronics and optoelectronics. My special interest focuses on measurements and analysis of magnetic and electric birefringence (Cotton-Mouton and Kerr effect); Magnification of electro- and magnetooptical values will result in experimental detection of new, theoretically predicted, magnetooptical and cross electro-magneto-optical effects, which cannot yet be observed because of their smallness. I am greatly interested small-angle X-ray diffraction studies of powdered and magnetically aligned samples; Magnetically correlated low-dimensional liquid-crystalline structures - columns, chains or planes are aggregates with magnetic anisotropy enhanced due to the spatial correlation. The correlation may take place due to the coordination (donor-acceptor) bonding of the metal atom with the neighboring molecules ligand, as well as due to the steric interactions. The steric factor and other interactions between adjacent metallomesogen molecules may serve as a reason for short molecular axes correlation which would lead to pronounced biaxiality of SA and even N phases. This correlation may noticeably change the mesophases magnetic anisotropy resulting in the anomalous magnetic-field orientation of the mesophase for some mesogens with the copper atom. It is very likely that the short axes correlation also takes place in the smectic (SA) phase of lanthanoid complexes possessing a record magnetic anisotropy. I have also studied the differential scanning calorimetry of phase transition. Another type of strongly correlated low-dimensional systems in metallomesogens may be realized in liquid crystals with low-spin (LS) to high-spin (HS) transitions. A high sensitivity of non-liquid-crystalline systems with spin transitions to external actions is well known. Creation of a bistable molecular assembly with liquid-crystalline properties would provide new possibilities in the field of sensor devices construction. Another field of my interest is computer simulation of molecular structure. The general purpose of this work is prediction of structure of large molecules. It is impossible to grow a perfect monocrystal of such compounds for X-ray measurements, and computer simulation is more simple way for investigation of its structure. |
