Phonon-mediated Casimir effect

The Casimir interaction is the fundamental physical phenomenon which emerges due to modification of vacuum fluctuations by boundaries in a confined area of space. It arises in many fields of physics, including condensed matter. Recently, substantial interest in the Casimir effect has revived as a result of the significant progress in the experimental techniques in cold atoms. In this thesis, we develop the description of the phonon-mediated Casimir interaction taking into account multiple phonon-impurity scatterings, that strongly renormalize the resulting interaction between the impurities. Our results, formulated in terms of the T-matrix formalism, generalize previous studies of the Casimir interaction between different kind of impurities and allow estimation of the expected phonon-induced Casimir interaction in various systems. Further, we consider a propagation of a singe hole in a two-dimensional ferromagnet accompanied by spin-flip processes. We show that an external magnetic field can be used to manipulate the properties of the single-layer system. For easy plain ferromagnets, at saturation value of the external field perpendicular to the easy axis, the Green’s function demonstrates the branch cut behavior. It is contrasted to the systems of an itinerant quasiparticle in the antiferromagnetic background where the quasiparticle retains the finite quasiparticle weight. The considered magnon scattering processes on a single itinerant electron (hole) in a two-dimensional ferromagnet can be used further for the magnon-mediated Casimir interaction in quasi-two-dimensional ferromagnets

Channeling of electrons and positrons in straight and periodically bent diamond(110) crystals

In this paper we present the results of a systematic numerical analysis of the channeling properties of electrons and positrons in oriented straight and periodically bent diamond(110) crystals. We analyse dependence of the intensity of the radiation emitted on the projectile energy as well as on the bending amplitude. The analysis presented is based on the grounds of accurate numerical simulations of the channeling process. The simulation parameters, such as the crystal orientation, thickness and bending parameters of the crystals as well as the energy of the projectiles, were chosen to match those used in past and ongoing experiments. The peculiarities which appear in the radiation spectra are attributed to the interplay of various radiation mechanisms. The analysis performed can be used to predict and explain future experimental results.Comment: 14 pages, 8 figures, 1 tabl

The Entry of the Novgorod Nobility into the Sovereign’s Court During the Reign of Mikhail Fedorovich

Introduction. The historical literature noted the active participation of the Novgorod nobility in the events of the Time of Troubles. The question of the fate of the Novgorod nobility during the reign of Mikhail Fedorovich has been much less studied. This article is devoted to the consideration of the question of the entry of representatives of the Novgorod nobility into the Sovereign’s court of Tsar Mikhail. Methods and materials. The article is based on the use and comprehensive analysis of the sources, which show the process of entry of the Novgorod nobility into the Sovereign’s court. The article uses documentary sources, including new archival materials. The author of the article uses the methods of prosopographic and historical-genealogical research. Analysis. The author of the article showed a very wide scale of the entry of the Novgorod nobles into the various ranks of the sovereign’s court. As a rule, those persons who deserted from Novgorod to the side of Moscow and faithfully served the Moscow authorities were granted to the court of Tsar Mikhail. By granting these nobles to serve at the court, the government of Tsar Mikhail had the goal of strengthening its political support. Results. The author comes to the conclusion that the enrollment of a number of representatives of the Novgorod nobility in the sovereign’s court led not to the strengthening, but to the weakening of the Novgorod service corporation as a whole, since it removed the most prominent and active nobles from its composition. Once in the sovereign’s court, people from Novgorod families gradually lost ties with the Novgorod nobility and sought to establish themselves in the new court environment