Magnetic properties of the insulating ferromagnetic phase in strained Pr_0.6Ca_0.4MnO_3 thin films

Bulk magnetization in Pr_{0.6}Ca_{0.4}MnO_3 thin films with tensile (SrTiO_3) and compressive (LaAlO_3) substrate-induced strain is compared to the magnetooptical Kerr effect (MOKE) measurements. In the absence of an external magnetic field, in both films, a stable ferromagnetic insulating majority phase coexists with an antiferromagnetic insulating phase below ~120K. MOKE measurements indicate that at 5K a metastable ferromagnetic metallic (FM) phase is formed at the surface of the stretched film in a magnetic field below 1.1T already, while in the bulk the FM phase starts to form in the field above ~4T in both films.Comment: Accepted in AP

Transparent boundary conditions for the nonlocal nonlinear Schroedinger equation: A model for reflectionless propagation of PT-symmetric solitons

We consider the problem of reflectionless propagation of PT-symmetric solitons described by the nonlocal nonlinear Schroedinger equation on a line in the framework of the concept of transparent boundary conditions for evolution equations. Transparent boundary conditions for the nonlocal nonlinear Schroedinger equation are derived. The absence of backscattering at the artificial boundaries is confirmed by the numerical implementation of the transparent boundary conditions

Ultrafast photoinduced phase separation dynamics in Pr(0.6)Ca(0.4)MnO(3) thin films

The time resolved Magnetooptical Kerr effect in the substrate-strain-induced insulating ferromagnetic phase in (Pr$_{0.6}$Ca$_{0.4}$)MnO$_3$ thin films on two different substrates was measured in a magnetic field up to 1.1T. The photoinduced Kerr rotation and ellipticity show remarkably different magnetic-field dependence. From the comparison of the magnetic field dependencies of the photoinduced and static Kerr rotation and ellipticity we conclude that a transient ferromagnetic metallic phase, embedded within the insulating ferromagnetic phase, is created upon the photoexcitation at low temperatures. A comparison of temporal dependence of the photoinduced Kerr signals with the photoinduced reflectivity indicates the change of the fractions of the phases takes place on a timescale of ten picoseconds independent of the substrate.Comment: accepted in EP

Practical aspect of comparative research on the material of the Russian and Tatar languages: XIX-XXI centuries

A major contribution of the scholars of the Kazan university to the field of contrastive study of the multistructural languages (including the Russian and Tatar languages) allows to reason about established long usage that is traced back to the beginning of the nineteenth century, further development prospect of comparative typology by Kazan scholars of the nineteenth century. The article aims at theoretical understanding and generalization of comparative studies, as well as consideration of the aspect of application of the studies to improve the methods of language teaching (Russian and Tatar). The article aims to make a comparative analysis by the material of Russian and Tatar, Tatar and Russian, reveal applied (linguistic and methodological) aspect of the results of the studies. The actuality of the problem consists in the fact that at the present stage the scholars do not remit their attention to the comparative studies, they direct the vector to comparing language pictures of the world of the native speakers of either language. The leading methods of our investigation are analysis, observation, description, generalization, classification. By results of the research the authors have reached a conclusion that today, all levels of the Russian and Tatar languages from the comparative aspect have been studied and the results have been presented in comparative grammars, research papers, dictionaries and so on. The comparison of language pictures of the world, national and cultural units of language at the level of text and discourse is presented to a lesser extent. New approaches allow to research into the level of contrastive cultural linguistics which has become an object of attention of Kazan scholars. We believe that this study makes a definite contribution to the field of comparative typology of the languages. Specialists in teaching methods of the Russian and Tatar languages as foreign may take interest in it

Ultrafast changes in lattice symmetry probed by coherent phonons

The electronic and structural properties of a material are strongly determined by its symmetry. Changing the symmetry via a photoinduced phase transition offers new ways to manipulate material properties on ultrafast timescales. However, in order to identify when and how fast these phase transitions occur, methods that can probe the symmetry change in the time domain are required. We show that a time-dependent change in the coherent phonon spectrum can probe a change in symmetry of the lattice potential, thus providing an all-optical probe of structural transitions. We examine the photoinduced structural phase transition in VO2 and show that, above the phase transition threshold, photoexcitation completely changes the lattice potential on an ultrafast timescale. The loss of the equilibrium-phase phonon modes occurs promptly, indicating a non-thermal pathway for the photoinduced phase transition, where a strong perturbation to the lattice potential changes its symmetry before ionic rearrangement has occurred.Comment: 14 pages 4 figure