Theory of the Interfacial Dzyaloshinskii-Moriya Interaction in Rashba Antiferromagnets

In antiferromagnetic (AFM) thin films, broken inversion symmetry or coupling to adjacent heavy metals can induce Dzyaloshinskii-Moriya (DM) interactions. Knowledge of the DM parameters is essential for understanding and designing exotic spin structures, such as hedgehog Skyrmions and chiral N\'eel walls, which are attractive for use in novel information storage technologies. We introduce a framework for computing the DM interaction in two-dimensional Rashba antiferromagnets. Unlike in Rashba ferromagnets, the DM interaction is not suppressed even at low temperatures. The material parameters control both the strength and the sign of the interfacial DM interaction. Our results suggest a route toward controlling the DM interaction in AFM materials by means of doping and electric fields.Comment: 4.5 pages+references, 4 figure

Nonequilibrium Magnons from Hot Electrons in Antiferromagnetic Systems

We describe a \emph{nonthermal} magnon activation mechanism in antiferromagnetic (AFM) systems via locally equilibrated \emph{spin-unpolarized} hot electrons excited by an ultrafast intense laser pulse. We employ a quantum kinetic equation that takes into account a direct electron-magnon scattering channel in either bulk AFM metal or at the interface of the AFM/normal-metal heterostructure. The mechanism is responsible for the nonequilibrium population of AFM magnon modes on a subnanosecond timescale, which are formed shortly after the local thermalization of hot electrons by Coulomb interactions. Nonequilibrium magnon populations can be additionally manipulated by applying an external magnetic field. Our work paves the way toward spin dynamics control in AFM systems via the ultrafast manipulation of out-of-equilibrium magnon excitations.Comment: 5.5 pages, 3 figures, Supplemental Material available as ancillary fil

Inertial dynamics and equilibrium correlation functions of magnetization at short times

The method of moments is developed and employed to analyze the equilibrium correlation functions of the magnetization of ferromagnetic nanoparticles in the case of inertial magnetization dynamics. The method is based on the Taylor series expansion of the correlation functions and the estimation of the expansion coefficients. This method significantly reduces the complexity of analysis of equilibrium correlation functions. Analytical expressions are derived for the first three coefficients for the longitudinal and transverse correlation functions for the uniaxial magnetocrystalline anisotropy of ferromagnetic nanoparticles with a longitudinal magnetic field. The limiting cases of very strong and negligibly weak external longitudinal fields are considered. The Gordon sum rule for inertial magnetization dynamics is discussed. In addition, we show that finite analytic series can be used as a simple and satisfactory approximation for the numerical calculation of correlation functions at short times

Modelando las operaciones de una empresa basadas en la ideología marginal

El artículo explora el tema de actualidad del modelado de operaciones empresariales con el uso del análisis marginal. La economía de mercado se caracteriza por la mayor inestabilidad del complejo sistema socioeconómico, que es casi imposible de comprender y estudiar por completo. Las empresas se enfrentan a una intensa competencia. Una adecuada toma de decisiones de gestión requiere evaluaciones exhaustivas en profundidad de la situación ypronósticos fiables. Una empresa que hace pronósticos correctos obtiene ganancias adicionales en comparación con una que se abstiene de pronosticar. Mientras tanto, una empresa que hace un pronóstico incorrecto es la que más pierde. Las decisiones gerenciales a menudo se basan en un análisis de equilibrio, i. e., análisis marginal. Este documento explora ejemplos en los que, incluso en los casos en que se toman decisiones desventajosas (como se muestra en el análisis de equilibrio), el entorno puede conducir a resultados positivos, i. e., al menos una ganancia moderada, a través de la validación de la decisión gerencial mediante análisis y cálculos adicionales. Se utilizaron los métodos de indagación, análisis retrospectivo y documental, así como síntesis, generalización y sistematizació

Modelando las operaciones de una empresa basadas en la ideología marginal

The paper explores the topical subject of modeling enterprise operations with the use of marginal analysis. The market economy is characterised by the heightened instability of the complex socioeconomic system, which is almost impossible to fully grasp and study. Businesses face intense competition. Adequate managerial decision-making requires in-depth comprehensive assessments of the situation and reliable forecasting. A firm that makes correct forecasts gains additional profit compared to one abstaining from forecasting. Meanwhile, a firm making an incorrect forecast loses most of all. Managerial decisions often rely on break-even analysis, i. e., marginal analysis. This paper explores examples where even in cases when disadvantageous choices are made (as shown by break-even analysis), the setting can still lead to positive results, i. e., at least a moderate profit, through the validation of the managerial decision by further analysis and calculations. The methods of enquiry, retrospective and document analysis, as well as synthesis, generalisation and systematisation were used.El artículo explora el tema de actualidad del modelado de operaciones empresariales con el uso del análisis marginal. La economía de mercado se caracteriza por la mayor inestabilidad del complejo sistema socioeconómico, que es casi imposible de comprender y estudiar por completo. Las empresas se enfrentan a una intensa competencia. Una adecuada toma de decisiones de gestión requiere evaluaciones exhaustivas en profundidad de la situación y pronósticos fiables. Una empresa que hace pronósticos correctos obtiene ganancias adicionales en comparación con una que se abstiene de pronosticar. Mientras tanto, una empresa que hace un pronóstico incorrecto es la que más pierde. Las decisiones gerenciales a menudo se basan en un análisis de equilibrio, i. e., análisis marginal. Este documento explora ejemplos en los que, incluso en los casos en que se toman decisiones desventajosas (como se muestra en el análisis de equilibrio), el entorno puede conducir a resultados positivos, i. e., al menos una ganancia moderada, a través de la validación de la decisión gerencial mediante análisis y cálculos adicionales. Se utilizaron los métodos de indagación, análisis retrospectivo y documental, así como síntesis, generalización y sistematización

Socioeconomic Development: Search For Optimal Models For Forecasting Inflationary Processes

The article is devoted to the analysis of the forecasting models for inflationary processes. The monetarist approach to inflation has been discussed in the article, and the inflation forecasting tools have been classified. Various inflation forecasting models have been studied, namely, one-factor models, Phillips-curve-motivated forecasts, vector autoregressive models, and dynamic models of general equilibrium. Comparative characteristics of the quality of the inflation forecasting models have been provided

Optical properties and structure particularities of LiNbO3 crystals grown from a boron-doped melt

A series of LiNbO3:B crystals was grown from the melt doped by boron. It is shown that LiNbO3:B crystals possess an increased resistance to optical damage. We have found changes according to Raman spectra confirming the ordering of Li+, Nb5+ cations and vacancies along the polar axis. The chemical interactions were studied in the system Li2O–B2O3–Nb2O5. Boron cations are unable to incorporate into a cation sublattice of LiNbO3, but they change the physic-chemical structure of a melt. It contributes to an increased structure and optical uniformity of LiNbO3:B.Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Statistics of S-matrix poles for chaotic systems with broken time reversal invariance: a conjecture

In the framework of a random matrix description of chaotic quantum scattering the positions of $S-$matrix poles are given by complex eigenvalues $Z_i$ of an effective non-Hermitian random-matrix Hamiltonian. We put forward a conjecture on statistics of $Z_i$ for systems with broken time-reversal invariance and verify that it allows to reproduce statistical characteristics of Wigner time delays known from independent calculations. We analyze the ensuing two-point statistical measures as e.g. spectral form factor and the number variance. In addition we find the density of complex eigenvalues of real asymmetric matrices generalizing the recent result by Efetov\cite{Efnh}.Comment: 4 page