Physics of Metals and Metallography

The magnetic properties of multilayer Fe20Ni80 films with magnetic anisotropy induced in the plane of the samples by oblique sputtering were studied. The sputtering process provided orthogonal orientation of
the magnetic anisotropy axes of adjacent layers. In two-layer films, the upper FeNi layer determined the formation of the resulting magnetic anisotropy of the sample. When the number of layers was increased to four, the resulting anisotropy axis was oriented at an angle of 45◦ to the anisotropy axes of the individual
layers. A non-monotonic change in the magnetic state of the multilayer film structure [FeNi/Cr]×4 was observed with increasing Cr spacer thickness.

This paper is devoted to the investigation of parametric autoresonance of spin waves in ferromagnets with easy-axis anisotropy. It is assumed that both the constant and alternating magnetic fields are oriented along the anisotropy axis. The threshold values of the amplitude of the alternating magnetic field required for
autoresonance excitation have been determined. It is shown that the autoresonance perturbation at the final stage transforms uniform spin oscillations into a spin wave. In the intermediate stage of the transformation process, near the resonance region, stable, highly nonlinear structures of the dark soliton type are formed. The influence of dissipation on the autoresonance process is discussed.

This paper discusses a new approach to modeling the magnetic behavior of a Heusler alloy. The magnetization distribution in a sample is obtained by solving an equation that determines the resulting direction of the magnetization vector. This equation follows from the Landau–Lifshitz–Gilbert equation, which describes the entire process history. The demagnetization field is defined through a scalar magnetic potential using magnetostatic equations. These equations are associated with variational equations, which in many cases allows us to reduce the requirements for the smoothness of the desired solution and is very convenient for the numerical implementation of the problem. An iterative algorithm for sequentially refining the magnetization and potential is proposed. Numerical modeling of the steady-state magnetization distribution within a two-dimensional sample is performed, as well as the demagnetization field both within the sample and in the surrounding space for various external magnetic field values.

In this work, the influence of the thicknesses of ferromagnetic and antiferromagnetic layers on the magnetic properties of the synthesized Pt/Co/FeMn/Pt structure on a SiO2 silicon substrate was investigated.
Magnetic hysteresis loops, angular dependencies of ferromagnetic resonance spectra, and the expression for the resonance field obtained by solving the Landau–Lifshitz equation for magnetization dynamics were used for experimental and theoretical studies. The coercive field values, as well as the unidirectional and uniaxial anisotropy fields, were determined for antiferromagnetic layer thicknesses of 5, 10, and 15 nm and ferromagnetic layer thicknesses of 5 and 10 nm. Suppression of uniaxial anisotropy and coercive field in the ferromagnetic layer with an increase in unidirectional anisotropy in Pt/Co/FeMn/Pt structures was observed, which is associated with enhanced exchange interaction between AFM and FM layers. The obtained results highlight the potential of using AFM/FM heterostructures in spintronic devices.

In this work, based on the exact solution of the Ising model on a decorated square lattice with an arbitrary number of decorating spins, the fundamental possibility of describing the phenomenon of magnetic reentrancy is revealed. It is established that magnetic reentrancy arises in the case of competition between exchange interactions in the considered spin systems. It has been found that in the system under study, only one, three, or five magnetic phase transitions are possible, which is confirmed by a complex magnetic phase diagram. A number of key scenarios for the formation of magnetic reentrancy are presented, illustrating the influence of model parameters on the magnetic behaviour of the system.

Despite the continuously expanding volume of experimental data on ultrafine-grained materials
produced by severe plastic deformation, the occurrence of competing structure-forming processes (strengthening/relaxation) still requires a theoretical explanation. Based on the analysis of hardness data for
technically pure copper subjected to shear under pressure in Bridgman anvils, the staging of strengthening was established. To account for the stochastic nature of the manifestation of relaxation processes during deformation, a model for analyzing material hardness data has been proposed, which is based on three postulates: (a) the structural response to hardness measurement, characteristic of its micro/nanostructural state, including the possible occurrence of a relaxation process, is considered as a random factor; (b) each structural state can be associated with its unique set of responses to hardness measurement; (c) the superposition of structural states is possible. It was shown that each structural response to hardness measurement can be associated with a specific structural state. Meanwhile, the evolution of hardness with applied deformation is a sequential change of combinations of three structural states (cell structure, microcrystalline without significant influence of dynamic recrystallization, and one formed by dynamic
recrystallization), which determine the stages of strain hardening.

A new approach of doping indium–gallium–zinc oxide (IGZO) with antimony was suggested and applied. The materials were obtained by decomposing a nitrate-tartrate complex using tartaric acid as a complexing agent. The phase composition and morphology of the doped materials were studied using x-ray diffractometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy and transmission electron microscopy methods. Physical parameters of the doped oxides, such as the band gap width (according to UV spectrophotometry data) and electrical resistivity, were determined.