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Specific features of the magnetic structure of the BiFeO3 multiferroic have been investigated by Mössbauer spectroscopy in the temperature range of 150–450 K. The temperature dependence of the anharmonicity parameter of the cycloidal spatial spin-modulated structure has been measured, and the magnetic anisotropy constant has been estimated.

Hyperfine interactions in the Bi1−xLaxFeO3 ferrites (where x = 0.0225, 0.075, 0.9) have been studied by means of 57Fe Mössbauer spectroscopy and 140Ce time differential perturbed angular γ–γ correlation methods. The information about the line shift δ, the lattice εlat and the magnetic εmag contributions to the quadrupole shift ε, isotropic His and anisotropic Han contributions to the hyperfine magnetic field Hhf on 57Fe nuclei, anharmonicity parameter m, distribution of the hyperfine magnetic field p(Hhf), and supertransferred hyperfine magnetic fields on 140Ce probe nuclei were obtained. In all studied compounds, the Fe ions are in a high-spin trivalent state. In the compounds with x = 0.0225 and 0.075 spatially modulated cycloidal magnetic structures exist. It was found that the sign of the effective constant of magnetic anisotropy Keff changes with the variation of x from 0.0225 to 0.075. The substitution of Bi by La increases the value of the hyperfine magnetic field on 57Fe nuclei from 494 kOe in Bi0.9775La0.0225FeO3 to 520 kOe in Bi0.1La0.9FeO3, i.e. by 26 kOe, while the corresponding supertransferred hyperfine magnetic field on 140Ce probe nuclei decreases.

AbstractIn this paper, the authors synthesize and study the phase formation of yttrium–iron garnet (YIG) using the supercritical antisolvent precipitation technique (SAS) at the initial stage for the first time. The effect of supercritical CO2 on the solution of acetates in the quasi-equilibrium state causes an abnormally high mobility of the structure’s elements. As a result, it becomes possible to form the equilibrium phase of the YIG solid product directly (without the appearance of transition oxides) at temperatures much lower than by solid-phase synthesis. The temperature decrease is due to a significant decrease in the activation energy of the solid solution.

Abstract—One of the problems in forecasting of news events is the development of models that allow working with a weakly structured information space of text documents. A distinctive feature of such a news space is the stochastic nature of the processes in it, the presence of memory, and the possibility of self-organization of information. It is interesting to develop a model for predicting events on the basis of a stochastic dynamics of the changing of images (or the state of the information space) of news clusters with allowance for memory and self-organization. The article discusses the schemes of transition probabilities between states in the information space, on the basis of which a nonlinear second-order differential equation is derived and a boundary value problem for predicting news events is formulated and solved. The analysis of the model described in the article shows the possibility of an increase in the probability of reaching the predicted event almost immediately after the beginning of the process of changing the structure of news clusters and the presence of abrupt jumps and oscillations in the probability of reaching an event.

An original theoretical method for the study of reflection of a plane electromagnetic wave from a plane-layered structure consisting of anisotropic films is used to develop optical modulators and tunable sensors. Relatively low switching voltages of modulators allow applications of such units in modern ICs and make it possible to construct high-rate optical channels for data transmission that connect fragments of a single IC or remote devices.

A design for a high-sensitivity photodetector with a single layer of MoS 2 transition-metal dichalcogenide used as the basic functional element is proposed and the process of its fabrication is presented step by step. Quality evaluation and the selection of functional MoS 2 flakes is based on the results of combined optical characterization. The main operating characteristics of the fabricated device are investigated and a photosensitivity of 1.4 mA/W is demonstrated. A difference of this device in comparison with existing analogues is its high photosensitivity at low operating voltages (in the range of ±3 V).

AbstractWide-range measurements of thin films of SiCxOyHz organosilicate glasses, both dense and porous, deposited on dielectric sapphire substrates and conductive layers of platinum and aluminum, were performed in the THz–IR (5–5000 cm–1) range. This method can be used not only to analyze the evolution of absorption bands in amorphous dielectric films but also to evaluate static conductivity in the framework of the Drude model of conductive layers and to determine the electrodynamic characteristics of organosilicate films with low dielectric permittivity. The original approach proposes a comprehensive analysis of experimental broadband data in order to determine not only the parameters of the individual bands of lattice and molecular vibrations but also the integrated electrodynamic characteristics of the samples obtained.

A modified Schottky-barrier model, which is nonlinear in terms of the surface-state concentration and contains a local quasi-Fermi level at the interface induced by excess surface charge, is proposed. Such an approach makes it possible to explain the observed similarity of the I–V characteristics of diodes with the Schottky barrier M/(SiC) 1– x (AlN) x and those of heterojunctions based on SiC and its solid solutions taking into account Φ g ≈ Φ B . The results of calculations of the Schottky-barrier heights are consistent with the experimental data obtained from measurements of the photocurrent for metals (M): Al, Ti, Cr, and Ni. The I–V characteristics in the composite–additive model of charge transport agree with the experimental data for the n -M/ p -(SiC) 1– x (AlN) x and n -6 H -SiC/ p -(SiC) 0.85 (AlN) 0.15 systems.

AbstractIt has been shown that the difference in the structure of electronic orbitals of silicon and germanium atoms is a decisive factor responsible for the formation of porous layers during their electrochemical etching in solutions of hydrofluoric acid.

Thin ferroelectric Pb(Zr0.48Ti0.52)O3 lead zirconate titanate films have been prepared on platinized silicon substrates via chemical solution deposition. The starting film-forming solutions were prepared by reacting lead acetate with Ti and Zr alkoxides in 2-methoxyethanol. The electrical properties of the films were shown to depend on the Ti and Zr alkoxide precursors used in synthesis. The nature of the zirconium alkoxide had the strongest effect on the properties of the films. The best properties were obtained with zirconium n-propoxide.