Vol 89, No 4 (2025)
Magnetism and Magnetic Materials
Micromagnetic modeling of hysteresis characteristics of suevites of the Zhamanshin impact crater
Abstract
On the basis of coordinated theoretical modelling using two independent models that take into account possible chemical inhomogeneity of particles and magnetostatic interaction between them, we calculated the hysteresis characteristics of suevites of the impact crater Zhamanshin corresponding to the experimental data and estimated the concentrations of ferrimagnetic particles in the samples.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):508-513
508-513
Longitudinal magnetoresistance of Ta/FeMn/Ta, Ta/Dy/Ta and Ta/CoFe/Ta nanostructures caused by the spin hall effect
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):514-521
514-521
Influence of the Al2O3 layer on the structural and temperature-dependent magnetic properties of thin cobalt films
Abstract
We studied cobalt films deposited by the magnetron method on an amorphous Al2O3 layer. The morphological and magnetic features associated with the formation of a naturally oxidized antiferromagnetic film on cobalt and the Al2O3/Co interface were studied. A change in the sign of the exchange bias at temperatures below 200 K was detected when the thickness of the cobalt layer on the Al2O3 film increased to more than 10 nm.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):522-527
522-527
Thickness dependencies of the coercivity of three-layer magnetic films obtained by chemical deposition
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):528-532
528-532
Study of magneto-optical properties of aromatic liquids and their application in signal processing
Abstract
Experimental results of Faraday rotation spectra in the range of 1.8–3.65 eV were obtained for H2O, CCl4, dimethylaniline, benzene, nitrobenzene, o-toluidine, o-anisidine, m-chloroaniline and o-chloroaniline. Semi-empirical quantum mechanical self-consistent field (SCF) calculations using the MNDO/D method for organic molecules were chosen to evaluate electronic spectra in the visible range for interpretation of experimental results. It is shown that the magneto-optical response of samples varies not only depending on geometry. distribution of pi electrons in aromatic liquids, but also significantly depends on their chemical composition.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):533-538
533-538
Temperature dependencies of magnetization and hysteresis loops of composite films (CoFeB+SiO2) with different compositions and structure
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):539-545
539-545
Magnetic dynamics of nickel films with a square stripe structure under excitation by acoustic pulses
Abstract
We studied the conditions for magnetization reorientation of nickel nanofilms with a jagged strip structure when acoustic pulses of a Gaussian shape pass through them. The behavior of such films in a constant magnetic field is studied, hysteresis loops are constructed depending on the angle of field application. The modeling was carried out using the MuMax3 software package. The results of the work can be used in the development of modern compact and energy-efficient magnetic recording devices.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):546-551
546-551
Magnetism of R-Co (R = Gd, Tb) films with high concentration of rare earth elements
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):552-558
552-558
Critical switching characteristics of the spin-valve structure in the arbitrary-direction magnetic field
Abstract
The dependences of the spin-valve critical switching field with planar and perpendicular anisotropy of layers on the anisotropy coefficient and the magnetic-field direction are analytically and numerically obtained. It is established that the smallest critical values of the field and switching time are achieved when the magnetic field deviates from the anisotropy axis by an angle of 45°.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):559-566
559-566
Influence of temperature on magnetoelectric effect in a structure containing langatate
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):567-571
567-571
Structure and magnetic properties of the medium-entropy GdTbDyY alloy
Abstract
A multicomponent rare-earth alloy GdTbDyY with a single-phase HCP crystal structure was synthesized. It was found that this alloy exhibits two magnetic phase transitions at temperatures of 140 and 201 K. Within the temperature range that encompasses both transitions, there was a noticeable magnetocaloric effect. It has been established that trivalent terbium and dysprosium ions contribute significantly to the magnetic properties of the GdTbDyY alloy: there is a correlation between structural and magnetic parameters.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):572-577
572-577
Optical properties of magnetoplasmonic microdiscs
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):578-584
578-584
Magnetoelectric response of a polymer composite filled with a mixture of CoFe2O4/BaTiO3 particles
Abstract
We studied the magnetoelectric response of a composite material based on a rubber-like polymer filled with submicron-sized cobalt ferrite and barium titanate particles. Using a computer experiment, the dependence of the magnetoelectric response of a representative volume of such a composite on the system parameters is studied. Based on the results of the computer experiment, methods for enhancing the magnetoelectric response of such composites are proposed.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):585-590
585-590
Radiation changes of structure and magnetic properties of barium hexaferrite
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):591-596
591-596
Study of magnetic interactions in a composite with a mixture of γ-Fe2O3 and CoFe2O4 nanoparticles
Abstract
We studied magnetic interactions in promising biomedical composites based on a piezoactive PVDF matrix with a mixture of soft magnetic γ-Fe2O3 (FO) and hard magnetic CoFe2O4 (CFO) nanoparticles by conducting IRM-DCD and FORC analyses. It was determined that the addition of a mixture of soft and hard magnetic nanoparticles to the polymer base of the composite leads to an increase in the magnetic interaction fields ΔHu from ≈1300 to ≈1500 Oe and to the formation of two main magnetic phases in the composite.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):597-603
597-603
Enhancement of magnetoelectric response in composite based on polyvinylidene fluoride and cobalt ferrite suspension due to nanoparticle dispersion
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):604-608
604-608
Influence of annealing under load on magneto-optical properties of iron-based nanocrystalline ribbons
Abstract
The results of the influence of load annealing on the magneto-optical properties of soft magnetic nanocrystalline e68.5Cr5Si13.5B9Nb3Cu1 ribbons obtained by rapid quenching from the melt and then annealed at a temperature of 520°C for 2 h without load and using a specific load of 150 MPa are presented. The near-surface magnetic hysteresis loops and simultaneous visualization of the changes of magnetic domain structure were measured using a magneto-optical Kerr magnetometer. The obtained experimental data that annealing underload leads to the formation of induced magnetic anisotropy and affects the magnetic field behavior of the samples.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):609-614
609-614
Wave Phenomena: Physics and Applications
Low-frequency Raman spectroscopy of human hair keratins
Abstract
Low-frequency Raman lines characterizing vibrations of elements of the secondary structure of fibrillar proteins (keratins) are identified. Experiments with unpigmented human hair are performed in two configurations: with excitation radiation focused coaxially with the hair and perpendicularly to it. Based on polarization sensitivity, the bands at frequencies of 150 and 221 cm-1 are assigned to vibrations of the α-helical structures of keratins. Spectral interval of 270–340 cm-1 is assigned to vibrations of β-structures.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):616-620
616-620
Algorithm for spatial-spectral data correction captured by a multispectral camera
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):621-626
621-626
Adequacy criteria for non-radiative limit in numerical studies of rarified plasma
Abstract
The characteristic features of Darwin’s (non-radiative) description of electromagnetic fields are considered. Criteria for the physical adequacy of the formalism are obtained within the framework of a self-consistent approach to the model representation of nonlinear processes of rarefied plasma. The implementation of the proposed estimates of the adequacy of the non-radiative approximation based on numerical researches of the Weibel instability.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):627-631
627-631
Radiation spectra and the quality evaluation of a high-power laser diode when entering the operating mode
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):632-636
632-636
On the possibility of propagating a solitary electromagnetic wave in arbitrary directions in the plane of a two-dimensional graphene-based superlattice
Abstract
The possibility of propagation of a plane solitary electromagnetic wave in the plane of a square two-dimensional graphene-based superlattice at various angles to its axes is investigated. A nonlinear equation describing the vector potential of a solitary electromagnetic wave is obtained for the case of weak nonadditivity of the energy spectrum of charge carriers in the collisionless approximation. It is shown that the propagation of plane solitary waves is possible either along the axes of the superlattice or at an angle of 45° to them.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):637-641
637-641
The design of tunable acoustic metamaterials using scattering theory methods
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):642-648
642-648
Hybridization of acoustic Tamm states and defective modes of one-dimensional phonon crystal
Abstract
The spectral properties of a one-dimensional phonon crystal bounded by a reflector in the form of an air layer are studied. The presence of a defect in a phonon crystal with a reflector at the edge leads to a connection between the defective mode and the acoustic Tamm state. This connection of modes of different nature manifests itself in the form of hybridization of modes, and the pushing apart of dips in the reflection spectrum is explained by avoided crossing of modes.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):649-653
649-653
Features of acoustic wave propagation in narrow pipes of variable cross-section, allowing for the added mass
Abstract
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.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):654-659
654-659
Propagation of spin waves in nanoscale bonded ferrite films
Abstract
Using micromagnetic modeling methods the propagation of spin waves in two nanoscale laterally bonded ferrite films was studied. The features of the power pumping of surface and backward volume magnetostatic waves are investigated. The effect of the distance between the films and the films' width of the films on the pumping length and cutoff frequency of these types of waves has been established.
Izvestiâ Akademii nauk SSSR. Seriâ fizičeskaâ. 2025;89(4):660-666
660-666