Том 89, № 4 (2025)

For Ta/Fe50Mn50/Ta, Ta/Dy/Ta, and Ta/Co90Fe10/Ta nanostructures prepared by magnetron sputtering, a positive longitudinal magnetoresistance due to the spin Hall effect was found. The difference in the magnitude of magnetoresistance and the shape of magnetoresistive curves obtained for nanostructures with layers of metals with different types of magnetic ordering is interpreted under the assumption of different magnitude of purely spin current injected into the magnetics layer.

The results of the study of the coercivity of three-layer magnetic films obtained by chemical deposition are presented. The features of its changes from the thickness of the forming layers are determined. They are associated with the specificity of the magnetization reversal of the studied system, caused by a small difference in the values of the coercivity of the magnetic layers. The energy of the demagnetizing field is calculated, since an expression for the critical field for the magnetization reversal of the film is obtained, which describes well the experimentally observed linear dependence of the coercivity on the thickness of the magnetic layers.

Temperature dependences of magnetization of composite films ((CoFeB+SiO2) with different concentrations of metal alloy x = 45–85 at. % with different micro- and nanostructure at temperatures of 2–400 K in magnetic fields of 5 mT and 5 T were obtained. Hysteresis loops of magnetization of films with different x in magnetic fields up to 5 T at temperatures of 2, 100, 300, and 400 K were obtained. It was shown that films with granular structure are characterized by a wider hysteresis loop and have a stronger dependence of magnetization on temperature compared to films with granular-percolation structure and films with a structure in the form of a metal matrix with dielectric inclusions.

We studied magnetic properties of R-Co (R = Gd, Tb) films containing up to 50 at. % cobalt. The X-ray diffraction characteristics of samples, temperature dependences of magnetization for films of different compositions, concentration dependences of Curie temperature and hysteresis properties are presented. The interpretation of the established patterns is given.

The effect of temperature on the linear magnetoelectric response in a three-layered composite structure comprising a single crystal of langatate with thin films of an amorphous ferromagnetic alloy deposited on either side was investigated. Measurements were conducted in the temperature range of 220–340 K. As a result, a linear reduction in the magnetoelectric coupling coefficient and sensitivity to a magnetic field with an increase in temperature was observed.

We investigated the polarizability, optical density spectra, and photothermal properties of Au/Fe/Au and Fe/Au/Fe layered microdisks synthesized by lift-off optical lithography. An analytical method for determining the electric polarizability in the quasi-static approximation is proposed. Theoretical and experimental results are consistent in the visible and near-IR spectral ranges. The results obtained provide an assessment of the applicability of such microdisks for combined photothermal and magnetomechanical anticancer therapy.

The effect of gamma irradiation and electron irradiation on the crystal structure and magnetic properties of barium hexaferrite BaFe12O19 (solid-phase synthesis) was studied. Irradiations caused changes in the ratio of crystalline phases and crystallite sizes, which resulted in changes in the main parameters of the hysteresis loop: coercive force, residual magnetization, saturation magnetization. These changes were non-monotonic depending on the dose, especially immediately after irradiation. In particular, the saturation magnetization measured at 300 K after γ-irradiation of the sample with a dose of 2.1·107 P decreased from the initial value of 52.5 to ~ 40.2 emu/g.

We presented the results of the study of a nanocomposite of polyvinylidene fluoride and cobalt ferrite nanoparticles coated with oleic acid. It is found that the nanocomposite has low porosity and highly dispersed distribution of nanoparticles in the polymer matrix, due to which it exhibits a strong effect for polymer-based magnetoelectric composites — 24.5 mV/(cm·E). This makes the studied material promising for use in biomedical applications as a scaffold for cell stimulation.

Imaging spectrometers provide non-contact and high-performance assessment of the physical and chemical object properties distribution, the effectiveness of which depends on the data accuracy obtained by the device. The paper introduces a method to correct spatial-spectral distortions in images captured by the imaging spectrometer based on the optical aperture division.

A method for evaluating the quality of the heterostructure of a high-power 200 MW laser diode based on measurements of radiation intensity spectra in the over-threshold generation mode is proposed. The method is based on the fixation and analysis of groups of generation modes related to spatial radiation channels. The spectra are measured at different pumping currents, which are lower than the standard, for a short (no more than 30 min) time interval.

A two-step method for designing acoustic metamaterials and calculating wave fields inside them is proposed. In the first step, the scattering coefficients are calculated, and in the second step, the specific design of the metamaterial elements is determined. The results of modeling a cloaking insulating shell and a lens with a tunable focus are presented.

The phenomena arising during the propagation of acoustic waves in narrow tubes with variable cross-section are studied. A special law of cross-sectional variation has been defined for the tube. The mode of wave tunneling through narrowing is investigated. The influence of the added mass on the boundaries of the narrowing area of the tube is taken into account. The frequency dependences of the coefficient of wave transmission over energy are constructed taking into account the added mass.