Department of Physics of Crystals was established by academician Antonina Prikhotko in 1944. Then the main research topic was low-temperature spectroscopy of molecular crystals. A cryogenic laboratory allowing for the studies at temperatures of liquefied nitrogen, hydrogen and helium has been found, the manufacturing basis of modern cryostat systems and corresponding measuring devices was organized to the first time in the world. In 50-ies – 70-ies it has grown up the leading in the USSR centre of the low-temperature spectroscopy of molecular crystals. Experimentally discovered and investigated collective character of light-induced electron excitations in molecular crystals triggered creation and provided background of the exciton theory in molecular crystals.
In addition, studies of superconducting materials with anomalously small charge density, a high-temperature superconductivity in which has become known later, have been carried out in the Department as well as a cryogenic medicine related research. For years it has been a schoolroom for many outstanding scientists; it was the Department of Physics of Crystals that gave birth to new departments: Optical Quantum Electronics (V.L.Broude, then M.S.Soskin), Nonlinear Optics (M.S.Brodyn), Photoactivity (M.T.Shpack, then G.O.Puchkovska), Resonance Phenomena (D.F.Baisa), Molecular Photoelectronics (M.V.Kuryk). Laboratory of Crystal Spectroscopy (G.V.Klimusheva) has been also established within the Department.
Investigations of liquid crystals started in the Department in the mid-80-ies have grown nowadays into its mainstream. Apparently, the most important and well-known achievement to a big extent associated with the department’s scientists has been the discovery of the “photoorientation” effect of liquid crystals on a polymer surface irradiated with polarized light that was done in collaboration with researchers from NIIOPIK (Russia). The effect of liquid crystal alignment caused by optical illumination of light-sensitive polymers provided vast opportunities for studying surface effects in liquid crystals allowing for the effective control of the principal characteristics of liquid crystal anchoring with boundary substrates. Therefore, a big fraction of recent papers was devoted to the investigations of light-induced changes of liquid crystal anchoring.
Furthermore, development together with the scientists from the Department of Gas Electronics of unconventional methods of liquid crystal alignment has brought forth different vacuum techniques utilizing anisotropic etching of substrates and deposition of new aligning layers with the beams of ions, neutral atoms, radicals and mixtures of these. Tentative studies of novel liquid crystalline materials are also carried out. Recent vigorous investigations are devoted to ionic liquid crystals on the base of metal-alkanoates focused on their structural, nonlinear-optical, thermophysical and electric properties. These materials, exhibiting the both lyotropic and thermotropic mesophases, form smectic phases as well as smectic ionic glasses, which could be employed for making unique anisotropic nano-composites. Recently a special attention is paid to investigations of low-concentrated colloids of nano-particles having different nature (ferromagnetic, polar dielectric, ferroelectric, low-dimensional conductors) suspended in liquid crystalline matrices.
Aggregation of nano-particles in such colloids proved to be infinitesimal, tiny particle dimensions prevent disturbance of liquid crystal orientation. Thus, optical quality of low-concentrated colloids appears to be not worse than that of the liquid crystalline matrix itself, while strong interaction of nano-particles with liquid crystal molecules gives rise to unique properties not inherent to the matrix. Experimental and theoretical studies of oxide superconductors have been also performing in the Department for many years.
A destructive interaction of superconductivity and charge density waves in these materials was discovered. Thermo- and electrodynamic theories of such materials were elaborated as well as a theory of Josephson and quasi-particle current in structures containing the investigated materials.
Fundamental and applied physics of liquid crystals, namely: nonlinear optics, surface phenomena, photonics, light scattering, electro- optical phenomena. Fundamental condensed matter physics, including theory of superconductivity.
The electronic properties of mesoscopic systems. Non-linear optics and photonics of polymers and molecular material layers.
- A distributed feedback laser on the basis of controlled holographic gratings (POLIPHEM®) has been created. According to theoretical analysis the modulation of the either, refraction or amplification gain coefficients bring out a substantial decrease of the generation threshold in such systems. Lasing at about 0.56 µm wavelength has been realized with laser radiation being tuned by electric field application. S.Slussarenko.
- A technique to produce tilted and planar alignment of liquid crystals on surfaces processed with an accelerated plasma beam was developed. Depending on the type of active particles of plasma such a treatment results in either an anisotropic etching of the orienting surface or a deposition of a new layer providing a high-quality orientation of a liquid crystal. The technique suffices the whole range of pretilt angles (0?90o) and a wide span of anchoring energies with an easy conversion for a large-area treatment required for LCD manufacturing. O.Yaroshchuk, R.Kravchuk.
- An effect of light-induced drift of the easy orientation axis has been discovered in an azo-dye-doped nematic liquid crystal. The axis drift results from light-induced adsorption/desorption of dye molecules on/from the boundary polymer surface in the presence of light-induced torque caused by orientational ordering of absorbing molecules of the dye. E.Ouskova, Yu.Reznikov, K.Slusarenko, D.Fedorenko.
- Liquid crystalline composites characterised with an essentially decreased off-axis haze in the electro-controlled light-scattering mode has been developed. The systems are based on polymer-dispersed nematic liquid crystals doped with inorganic nano-particles having large refractive index. It was shown that under phase separation appearing during polymerisation of pre-polymer nano-particles penetrate into the polymer matrix changing, thus, optical properties of the latter. L.Dolgov, O.Yaroshchuk.
- An effect of the increase of the nematic liquid crystal – isotropic liquid phase transition temperature at introduction into liquid crystal of ferroelectric nano-particles has been observed. The effect is accompanied with the enhancement of liquid crystal ordering that leads to the augmentation of dielectric anisotropy and birefringence of suspensions of ferroelectric nano-particles in liquid crystals. The results obtained allow for development of liquid crystalline materials, properties of which could be effectively modified by a non-chemical way. O.Buchnev, Yu.Reznikov, O.Tereshchenko.
- A surface-mediated efficient photorefractive effect in liquid crystals has been discovered and studied. The change of refractive index of liquid crystal under a simultaneous application of light and electric field was shown to originate from a spatial charge modulation at cell substrates. Such a spatial charge modulation brings forth an electric field component reorienting liquid crystal that, in turn, changes its refractive index. P.Korniychuk, Yu.Reznikov, V.Reshetnyak.
- A tunnel technique of experimental determination of spin polarisation in ferromagnetics has been proposed employing counter-electrodes made from metals with charge density waves. , O.Gabovych.
- An effect of electric field induced formation of bi-layer cell “nano-sized layer of electro-chromic dye (viologen) – lyotropic ionic liquid crystal” has been observed. Dynamic hologram recording characterised with nano-second times of the grating build up and decay was realised. The recording mechanism was shown to result from the effect of photoconversion of viologen dimmers into cation-radicals. Such materials are seemed to be promising for applications in devices for photonics, fast recording and processing of optical information. G.Klimusheva, S.Bugaychuk, Yu.Garbovsky.
- Techniques for fabrication of new composite materials based on mesomorphic glasses of metal-alkanoates with different organic and inorganic nano-clusters were developed. Parameters of smectic structure of these systems were determined by means of small-angle x-ray scattering. G.Klimusheva, A.Tolochko, V.Kulishov.
- O. Kurochkin, O. Buchnev, A. Iljin, S.K. Park, S.B. Kwon, O. Grabar and Yu. Reznikov. A colloid of ferroelectric nanoparticles in a cholesteric liquid crystal. J. Opt. A: Pure Appl. Opt., 11, 024003 (2009).
- A.B. Bordyuh, Yu.A.Garbovskiy, S.A.Bugaychuk, G.V.Klimusheva, T.A.Mirnaya, G.G.Yaremchuk, A.P.Polishchuk. Dynamic grating recording in lyotropic ionic smectics of metal alkanoates doped with electrochromic impurities, Opt.Mat. 31, (2009), 1109 – 1114.
- R.Conte and S.Bugaychuk, Explicit solutions of the four-wave mixing model. J. Phys. A: Math. Theor., 42, 192003 (2009).
- Denis Fedorenko, Kostyantyn Slyusarenko, Elena Ouskova, Victor Reshetnyak, KiRyong Ha, Ridvan Karapinar, and Yuriy Reznikov. Light-induced gliding of the easy orientation axis of a dye-doped nematic liquid crystal. Phys. Rev. E, 77, 061705 (2008).
- Rui Guo, Yuriy Reznikov, Kostyantyn Slyusarenko and Satyendra Kumar. Dynamics of molecular exchange between aligning adsorbed ?lm of liquid crystal and the bulk. Appl. Phys. Lett., 92, 121911 (2008).
- T. Ekino, A.M. Gabovich, Mai Suan Li, M. Pekala, H. Szymczak, A.I. Voitenko. Temperature-dependent pseudogap-like features in tunnel spectra of high-Tc cuprates as a manifestation of charge-density waves. J. Phys.: Cond. Matter, 20(42), 425218 (2008).
- Mai Suan Li, A.M. Gabovich, A.I. Voitenko. New method for deciphering free energy landscape of three-state proteins. J. Chem. Phys., 129(10), 105102 (2008).
- Oleg V. Yaroshchuk, Alexei D. Kiselev, and Ruslan M. Kravchuk, Liquid-Crystal Anchoring Transitions on Aligning Substrates Processed by a Plasma Beam, Phys. Rev. E., 77, 031706, (2008).
- O.Buchnev, A.Dyadyusha, M.Kaczmarek, V.Reshetnyak, and Yu.Reznikov. Enhanced two-beam coupling in colloids of ferroelectric nanoparticles in liquid crystals. J.Opt.Soc.Am.B 24(7), 1512 (2007).
- M.Copic, A.Mertelj, O.Buchnev, and Yu.Reznikov. Coupled director and polarization fluctuations in suspensions of ferroelectric nanoparticles in nematic liquid crystals. Phys.Rev.E, 76, 011702 (2007).
- Yu. Garbovskiy, A. Koval’chuk, A. Grydyakina, S. Bugaychuk, T. Mirnaya, G. Klimusheva, Electrical conductivity of lyotropic and thermotropic ionic liquid crystals consisting of metal alkanoates. Liquid Crystals, 34(5), 599 (2007).
- A.M. Gabovich and A.I. Voitenko. Charge-density-wave origin of the dip-hump structure in tunnel spectra of the BSCCO superconductor. Phys. Rev. B, 75(6), 064516 (2007).
- A. M. Gabovich, V. A. Drozd, M. Pekala, T. Ekino, R. Ribeiro. Competition between Superconductivity and Charge Carrier Localization in Plumbates. In: Superconductivity Research Advances, ISBN: 978-1-60021-691-6, Editor: James E. Nolan, pp. 149-193 (2007), Nova Science Publishers, Inc.
- F.Li, O.Buchnev, C.Il Cheon, A.Glushchenko, V.Reshetnyak, Yu.Reznikov, T.J.Sluckin, and J.L.West. Orientational Coupling Amplification in Ferroelectric Nematic Colloids. Phys.Rev.Lett., 97, 147801 (2006).
- P.Korneychuk, O.Tereshchenko, Yu.Reznikov, V.Reshetnyak, K.Singer. Hidden surface photorefractive gratings in a nematic-liquid crystal cell in the absence of a deposited alignment layer. J.Opt.Soc.Am.B, 23(6), 1007 (2006).
- J.L.West, K.Zhang, A.Glushchenko, D.Andrienko, M.Tasinkevych, and Y.Reznikov. Colloidal particles at a nematic-isotropic interface: Effects of confinement. Eur.Phys.J.E, 20, 237 (2006).
- A.Gabovich, Yu.Reznikov, and A.Voitenko. Excess nonspecific Coulomb ion adsorption at the metal electrode/electrolyte solution interface: Role of the surface layer. Phys.Rev.E, 73, 021606 (2006)
- D.Fedorenko, E.Ouskova, V.Reshetnyak, and Yu.Reznikov. Evolution of light-induced anchoring in dye-doped nematics: Experiment and model. Phys.Rev.E, 73, 031701 (2006)
- G.Klimusheva, S.Bugaychuk, Yu.Garbovskii, O.Kolesnik, T.Mirnaya, A.Ishchenko. Fast dynamic holographic recording based on conductivity ionic metal –alkanoate liquid crystals and smectic glasses. Optics Letters, 31, 235 (2006).
- O. Yaroshchuk, V. Chigrinov, O. Nadtoka, and H. Kwok, Factors of liquid crystal photoalignment on polymer films: photoorientation versus self-assembly, Liq.Crystals, 33 (2), 149 – 157 (2006).
- Jessica Merlin, Elysa Chao, Mark Winkler, Kenneth D. Singer, Platon Korneychuk and Yuri Reznikov. All-optical switching in a nematic liquid crystal twist cell. Opt. Exp.. 13, 5024 (2005)
- John L. West, Guoqiang Zhang, Anatoliy Glushchenko, and Yurii Reznikov. Fast birefringent mode stressed liquid crystal. Appl.Phys.Lett., 86, 031111 (2005)
- O. Yaroshchuk, L. Dolgov and A. Kiselev. Electro-optics and structural peculiarities of liquid crystal-nanoparticle-polymer composites. Phys.Rev.E., 72, 051715-1-051715-11 (2005).
(left to right) Curieuse Y.I. explores fotooriyentovani Cell polarizing microscope Y.A. Reznikov, Fedorenko D.V. conduct research director reorientation dynamics svitloindukovanoyi liquid crystal cell.
(left to right) graduate Korniychuk P.P., trainee Buchnyev O.S., Tereschenko O.H.
liquid crystal cell to produce
(left to right) Yaroschuk O.V. postgraduate Dolgov L.O. and Kravchuk R.M. (seated)
conduct measurements of the angle perednahylu director of liquid crystal cells.
Uskova O. asks the speaker at 3-one Christmas Conference liquid crystals (2003).
Slyusarenko S.S. reports on 3-one Christmas Conference liquid crystals (2003).
Preparing for Christmas 3-one conference with liquid crystals (2003).
(From left) Kravchuk R.M., Fedorenko D.V., Ryeznikov J.O.,
trainee Buchnyev O.S., Buluy O. G., Tereschenko O.H.