Spin-fluctuation theory beyond Gaussian approximation

A characteristic feature of the Gaussian approximation in the functional-integral approach to the spin-fluctuation theory is the jump phase transition to the paramagnetic state. We eliminate the jump and obtain a continuous second-order phase transition by taking into account high-order terms in the expansion of the free energy in powers of the fluctuating exchange field. The third-order term of the free energy renormalizes the mean field, and fourth-order term, responsible for the interaction of the fluctuations, renormalizes the spin susceptibility. The extended theory is applied to the calculation of magnetic properties of Fe-Ni Invar.Comment: 20 pages, 4 figure

Resonant photoemission spectroscopy of Cu(InGa)Se2 materials for solar cells

The electron structure of CuIn1 - x Ga x Se 2 single crystals is determined via resonant photoemis-sion and the main regularities of its transformation upon varying concentration x from 0 to 1 are established. The dependence of the shape of valence band spectra on the photon energy is studied. Integral photoemission intensities are shown to be determined by atomic photoionization cross sections. Processes of the direct and two-step creation of photoelectrons accompanying photoemission and the participation of internal states in the spectra of electrons from valence bands are studied. Two-hole final states in photoemission are obtained upon threshold excitation of the Cu 2p level. The strong interaction of holes leads to the multiplet splitting of these states. Partial densities of the components' states are determined using the energy dependence of atomic photoionization cross sections. © 2013 Allerton Press, Inc

Effects of spin polarization on resonant photoemission from d-f states in TbNi2Mnx compounds

Resonant photoemission in narrow-band materials is described by the sum of first-and secondorder transitions, their quantum-mechanical interference leads to an increase in the spectrum from the valence bands and the appearance of an asymmetric dependence on the photon energy. These effects are studied theoretically and experimentally using the example of three-component intermetallic compounds TbNi2Mnx. The competition between the elastic and inelastic photoemission channels leads to a different dependence of photoemission spectra from nickel and manganese on photon energy. The elastic channel is realized on atoms with large magnetic moments, the inelastic Auger decay occurs on atoms with small moments. © 2018 The Authors, published by EDP Sciences.The research was carried out within the state assignment of FASO of Russia (theme uQ" ant" No. 01201463332), supported in part by RFBR (No. 18-02-00060) and UD RAS (No.15 -8 2-10). The authors express their gratitude to A. Preobrazhenskii and N. Vinogradov (synchrotron MAX-Lab, Lund, Sweden) for their assistance in carrying out experiments

A photoelectron spectroscopy study of the electronic structure evolution in CuInSe2-related compounds at changing copper content

Evolution of the valence-band structure at gradually increasing copper content has been analysed by x-ray photoelectron spectroscopy (XPS) in In2Se3, CuIn5Se8, CuIn3Se5, and CuInSe2 single crystals. A comparison of these spectra with calculated total and angular-momentum resolved density-of-states (DOS) revealed the main trends of this evolution. The formation of the theoretically predicted gap between the bonding and non-bonding states has been observed in both experimental XPS spectra and theoretical DOS

Asymmetrical current generator operating modes in battery charging

This paper presents the investigation of the different operating modes of the asymmetrical quasi-sinusoidal output current inductive-switch generator. The purpose of investigation is to find the most effective operation mode where an acceptable output current quality is combined with relatively small dynamic losses in switches. Depending on the algorithm of the generator switches, there are four operating modes. The calculations describing the generator operating principle were obtained for each operating mode

Asymmetrical current generator operating modes in battery charging

This paper presents the investigation of the different operating modes of the asymmetrical quasi-sinusoidal output current inductive-switch generator. The purpose of investigation is to find the most effective operation mode where an acceptable output current quality is combined with relatively small dynamic losses in switches. Depending on the algorithm of the generator switches, there are four operating modes. The calculations describing the generator operating principle were obtained for each operating mode

Trajectory and stability of Lagrangian point L2L_2 in the Sun-Earth system

This paper describes design of the trajectory and analysis of the stability of collinear point $L_2$ in the Sun-Earth system. The modified restricted three body problem with additional gravitational potential from the belt is used as the model for the Sun-Earth system. The effect of radiation pressure of the Sun and oblate shape of the Earth are considered. The point $L_2$ is asymptotically stable upto a specific value of time $t$ correspond to each set of values of parameters and initial conditions. The results obtained from this study would be applicable to locate a satellite, a telescope or a space station around the point $L_2$.Comment: Accepted for publication in Astrophysics & Space Scienc

Social and philosophic foundations of youth nonconformity in contemporary Russia

© 2018, Ecozone, OAIMDD. All rights reserved. The purpose of this article is to consider and analyse various approaches to understand nonconformity in general and in the youth environment in particular in order to synthesize and learn from the data and knowledge obtained, and develop a more general and integrated perspective on its essence, determinacy and manifestation specifics. The results discussed in the paper deal with the social-and-philosophical point of view on the various approaches to understanding nonconformity both in a historical retrospect and in modern science. The study revealed that in recent decades the concept of nonconformity has lost its negative connotation. Different conceptual approaches used in studying the phenomenon indicate its significance in the society and personality development, its innovative potential to create and develop new social values, patterns of behaviour and moral standards in the dynamically changing world. Various forms of nonconformity manifestation specify the particularities of contemporary youth subcultures and their socializing potential. The materials of the paper may be of theoretical and practical value to develop programs and teaching materials on social philosophy, sociology and social psychology, as well as the programs connected with prevention of destructive forms of nonconformity in order to bring the processes of young people‘s social adaptation and socialization into compliance

Modelling Stochastic and Deterministic Behaviours in Virus Infection Dynamics

Many human infections with viruses such as human immunodeficiency virus type 1 (HIV--1) are characterized by low numbers of founder viruses for which the random effects and discrete nature of populations have a strong effect on the dynamics, e.g., extinction versus spread. It remains to be established whether HIV transmission is a stochastic process on the whole. In this study, we consider the simplest (so-called, 'consensus') virus dynamics model and develop a computational methodology for building an equivalent stochastic model based on Markov Chain accounting for random interactions between the components. The model is used to study the evolution of the probability densities for the virus and target cell populations. It predicts the probability of infection spread as a function of the number of the transmitted viruses. A hybrid algorithm is suggested to compute efficiently the dynamics in state space domain characterized by a mix of small and large species densities