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Bratkovsky A.M.,Hewlett - Packard | Levanyuk A.P.,Hewlett - Packard | Levanyuk A.P.,Autonomous University of Madrid | Levanyuk A.P.,Moscow Institute of Radioengineering
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We study cubic ferroelectrics films that become uniaxial with a polar axis perpendicular to the film because of a misfit strain due to the substrate. The main present result is the analytical account for the elastic anisotropy as well as the anisotropy of the electrostriction. They define, in particular, the orientation of the domain boundaries and the stabilizing or destabilizing effect of inhomogeneous elastic strains on the single domain state. We apply the general results to perovskite systems like BaTiO3/SrRuO 3/SrTiO3 films and find that, at least not far from the ferroelectric phase transition, the equilibrium domain structure consists of the stripes along the cubic axes or at 45° to them. We also show that, in this system, the inhomogeneous strains increase stability with regard to small fluctuations of the metastable single domain state, which may exist not very close to the ferroelectric transition. The latter analytical result is in qualitative agreement with the numerical result by Pertsev and Kohlstedt but we show that the effect is much smaller than those authors claim. We find also that under some conditions on the material constants, which are not satisfied in perovskites but are not forbidden, in principle, instead of the striped-like domain structure a checkerboard one can be realized and the polarization-strain coupling decreases the stability of a single domain state instead of increasing it. © 2011 American Physical Society. Source


Tychinsky V.P.,Moscow Institute of Radioengineering | Vyshenskaya T.V.,Moscow State University | Terpigorev S.A.,Mf Vladirairsky Moscow Region Research Clinical Institute | Vasilenko I.A.,Russian Gerontological Research Center | And 4 more authors.
Vestnik Rossiiskoi Akademii Meditsinskikh Nauk | Year: 2011

Investigation of initial stages of T-lymphocytes activation was performed by coherent phase microscopy (CPM) based on the measurements of phase thickness and diameter of the cell and its organelles. Lymphocytes where activated in two ways: by addition of 2 10-6 g/ml phytohemagglutinin (PHA) and with He-Ne laser (X=633 nm, 10-3 W) radiation. It was shown that phase thickness is proportional to refractivity (difference between refractive indices of an object and the surrounding medium) and geometrical thickness. Phase thickness decreased during activation independently of the nature of the stimuli. Phase thickness in healthy donors was 220+60 nm; decreased to 110+30nm lh after addition of PHA. The same values were achieved 30 min after stimulation with the He-Ne laser. Characteristic changes in phase thickness in the nucleus and nucleolus were observed after lymphocytes were stimulated with the laser. Source


Bush A.A.,Moscow Institute of Radioengineering | Glazkov V.N.,RAS Institute of Solid State Physics | Hagiwara M.,Osaka University | Kashiwagi T.,University of Tsukuba | And 6 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We present the results of the magnetization and dielectric constant measurements on untwinned single-crystal samples of the frustrated S=1/2 chain cuprate LiCu 2O 2. Magnetic phase transitions were observed. A spin-flop transition of the spiral spin plane was observed for the field orientations Ha, b. The second magnetic transition was observed at H-15 T for all three principal field directions. This high-field magnetic phase is discussed as a collinear spin-modulated phase, which is expected for an S=1/2 nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic chain system. © 2012 American Physical Society. Source


Sapoletova N.,Moscow State University | Makarevich T.,Moscow Institute of Radioengineering | Napolskii K.,Moscow State University | Mishina E.,Moscow Institute of Radioengineering | And 4 more authors.
Physical Chemistry Chemical Physics | Year: 2010

The kinetics of nickel electrodeposition through a template of ordered polystyrene spheres is addressed experimentally and applied to prepare a series of metallic inverse opals with a non-integer number of layers. The observed layer-by-layer growth is discussed in terms of subsequently increasing disorder of the growth front. Reflection and transmission spectra of the samples demonstrate that the key optical features of these photonic crystals are most pronounced when the thickness does not essentially exceed two layers. The intensities and band positions can be additionally tuned by varying the height of the metal coating continuously, not discretely. These findings are confirmed semi-quantitatively by means of computational modeling of the spectra. Specific deposition current transients for in situ control of geometric parameters are discussed. © 2010 the Owner Societies. Source


Gippius A.A.,Moscow State University | Tkachev A.V.,Moscow State University | Gervits N.E.,Moscow State University | Pokatilov V.S.,Moscow Institute of Radioengineering | And 2 more authors.
Solid State Communications | Year: 2012

BiFeO 3 is a perovskite-like compound with magnetic and electrical long-range order with antiferromagnetic transition temperature about 670 K. It has space modulated magnetic structure of cycloidal type with the period λ=620±20 incommensurate with the lattice parameter leading to specific NMR line shape. Substitution of strontium for bismuth atoms destroys the space modulated structure. Several samples with substitution of strontium for bismuth Bi 1-xSr xFeO 3 were studied by means of zero field NMR and Mssbauer spectroscopy. A significant broadening of 57Fe NMR spectrum was observed at x=0.10 while Mssbauer spectroscopy demonstrates this effect at x=0.07. This phenomena evidence for the destruction of the spatial modulated magnetic structure at x∼0.070.10 by the heterovalent substitution of strontium for bismuth without the destruction of crystal rhombohedral structure. © 2011 Elsevier Ltd. All rights reserved. Source

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