The article presents the results of magnetocrystalline anisotropy (MCA) investigation of Y2(FexCo1-x)17 (x = 0.03-0.50) rare-earth quasi-binary bulk crystal samples and their hydrides. The specific magnetization curves m (H) were measured in the wide temperature range for the original Y2(FexCo1-x)17 samples and for the corresponding hydrides. Magnetocrystalline anisotropy constants K1, K2 were calculated, temperature and compositional dependence curves were plotted based on m ( H ) data. The temperature dependences of specific saturation magnetization m s ( T ) and first anisotropy constant K 1 ( T ) were analyzed to determine temperature behavior patterns, estimate the Curie temperature Tc and predict the spin-reorientation transitions. The first anisotropy constant, saturation magnetization and Curie temperature compositional dependences of original Y2(FexCo1-x)17 and hydrogenated Y2(FexCo1-x)17Hy samples were compared to identify the hydrogenation effect on the magnetic properties of investigated compounds. The revealed patterns were explained in terms of the crystal structure of the compounds.

Nanoscale iron films of different thicknesses and at different spatial scales were studied using two alternative methods: atomic force microscopy and scanning tunneling microscopy. It was revealed that the surface morphology and fractal dimension depend not only on the film thickness but also on the deposition conditions and subsequent digital processing. It was concluded that the surface has a highly developed relief, which corresponds to high values of the fractal dimension. A hypothesis was put forward that the presence of iron oxides on the surface of the studied samples significantly affects their morphology, contributing to the formation of a complex and highly developed relief. These oxides lead to the formation of some structural inhomogeneities, which lead to the observation of agglomerates in a fairly wide range of fractal dimension values (from 2,49 to 2,94) on the film surface, i.e. oxides contribute to the aggregation of particles, creating a more complex surface structure. In addition, a method of separating agglomerates allowed us to record an increase in the value of the fractal dimension, which indicates the efficiency of separating and studying individual complex surface objects. Thus, for nanosized iron films, it becomes important to take into account the effects of oxidation and agglomeration of surface elements when analyzing them and choosing a method for obtaining them to identify structures with a certain value of the fractal dimension.

The results of an experimental study of the magnetic domain structure on the basal plane of RFe11Ti single crystals (R=Y, Gd, Ho, Er) by magnetic force microscopy are presented. At room temperature, the compounds are characterized by magnetocrystalline anisotropy of the "easy axis" type. Based on the magnetic force microscopy data, the sizes of domains on the basal plane of the samples were determined. Using the Bodenberger-Hubert method, the surface energy density of domain walls gamma was determined for all compounds based on the magnetic force microscopy data: YFe11Ti - 4,05 mJ/m(2), GdFe11Ti - 5,93 mJ/m(2), HoFe11Ti - 4,97 mJ/m(2), ErFe11Ti - 2,98 mJ/m(2). The cube counting method was used to calculate the fractal dimension D-L of the stray fields of the domain structure at different heights from the surface (0,1 - 9 mu m). D-L on the surface of the z(0) sections has values of 2,62 for compounds with R = Y, Gd, Ho and 2,72 for R=Er. For all samples, D-L has a maximum near the surface.

The study of the fractal properties of the surface of Nd100–xFex alloys in a wide range of concentrations х (х = 20–90) was carried out in the framework of the fractal thermodynamics model. To this end, we performed an analysis of images obtained by (scanning electron?) microscopy of the surfaces of a series of Nd100–xFex alloys synthesized by induction melting. A high degree of proximity of the surface structure of all the studied samples, both before and after etching, to fractals is shown. The values of the parameter δ characterizing the relative deviation of the studied samples from the fractal are in the range of 0.017–0.029. Three-dimensional diagrams of the fractal parameters Sf , Tf , Ef , x and two-dimensional diagrams of the same parameters: Sf , Tf , Ef , x, reflecting the nature of the state of the surfaces of Nd100–xFex alloy samples before and after etching, are constructed. For all investigated samples of alloys, the values of the parameters of the fractal equations of state arecalculated. The correlation of the maximum value of the coercive force Hc = 4.8 kE with the values of fractal entropy Sf = 39.86, fractal temperature Tf = 529, and fractal dimension D = 2.6530 of the Nd100–xFex alloys at x = 20 has been established.

The main aim of the present work is to analyze the magnetocrystalline anisotropy (MCA) energy function of uniaxial crystals and to derive analytical expressions for the domain wall (DW) energy taking into account two MCA constants. Thus, the article presents a detailed analysis of the magnetocrystalline anisotropy energy function of uniaxial crystals taking into account two MCA constants (K-1, K-2). The values of the MCA energy extremes and the position of the easy magnetization directions (EMD) and hard magnetization directions (HMD) were determined. The MCA diagram was plotted in "K-1"-"K-2" coordinates. Six types of MCA have been found for uniaxial crystals. Two of them are simple with one maximum and one minimum of the E-A(theta) function, and four are complex with two absolute and one local extreme for each. It is shown that E-A(K-1, K-2) function has the smallest difference between the maximum and minimum values equal to |K-1|/4 and the smallest angle between EMD and HMD equal to pi/4 when the K-1 + K-2 = 0 condition is met. Analytical expressions for the 180 degrees Bloch domain wall energy surface density (gamma) were derived for uniaxial crystals with each MCA type. It is found that the gamma(K-1, K-2) function has a minimum, equal to gamma=2 root A|K-1| when the relation K-1 + K-2 = 0 between MCA constants is satisfied. The derived analytical expressions are useful for a detailed spin-reorientation transition analysis. To illustrate this, examples of the application of the obtained results to MCA analyses of real crystals and DW energy calculations are given.

The study of the fractal properties of the surface of Nd100 – xFex alloys in a wide range of concentrations х (х = 20–90) was carried out in the framework of the fractal thermodynamics model. To this end, we performed an analysis of scanning electron microscopy images of the surfaces of a series of Nd100 – xFex alloys synthesized by induction melting. A high degree of proximity of the surface structure of all the studied samples, both before and after etching, to fractals is shown. The values of the parameter δ characterizing the relative deviation of the studied samples from the fractal are in the range of 0.017–0.029. Three-dimensional diagrams of the fractal parameters Sf, Tf, Ef, and x and two-dimensional diagrams of the same parameters Sf, Tf, Ef, and x reflecting the nature of the state of the surfaces of Nd100 – xFex alloy samples before and after etching are constructed. For all investigated alloy samples, the values of the parameters of the fractal equations of state are calculated. The correlation of the maximum value of the coercive force Hc = 4.8 kE with the values of fractal entropy Sf = 39.86, fractal temperature Tf = 529, and fractal dimension D = 2.6530 of the Nd100 – xFex alloys at x = 20 has been established.

The magnetization curves of the Y2(FexCo1 – x)17 compounds were measured in the temperature range of 300–923 K along easy and hard magnetization directions. The magnetization curves were analyzed, and the magnetocrystalline anisotropy constants K1, 2 of the samples were calculated. The temperature and composition dependences of the anisotropy constants K1, 2 and the saturation magnetization Ms were discussed. It was shown that, with increasing relative iron concentration in the samples, the first anisotropy constant K1 increases and reaches a maximum value of 5.1 × 105 J m–3 at x = 0.29.

The authors study the behavior of samples of (Gd,Zr)(CoCuFe)z alloy in magnetic fields oriented at different angles to their easy magnetization axes. The angular dependences of magnetization and coercivity are built. The hysteresis loops for the two main structural components of the samples are plotted using images of domain structure in demagnetizing fields. Results are analyzed by assuming there is a mixed mechanism of hysteresis in this family of alloys.

The authors study magnetic properties of Heusler alloys with composition Ni54.4Mn17.6Ga26.2Si1.8 subjected to multiple isothermal forging. It is found that multiple isothermal forging shifts the temperatures of structural and magnetic phase transitions toward low values. Magnetization and the magnetocaloric effect are reduced slightly, and there is a qualitative change in the structure of the magnetic domain.

Results are presented from studying magnetization and remagnetization in single-crystal samples of GdCo4Cu alloy. The coexistence of two hysteresis mechanisms is observed, depending on the magnetic background. Abrupt remagnetization is observed along with strong magnetic viscosity. The relationship between hysteresis processes and the structural states of samples is discussed.

The article continues a series of studies of permanent magnets with different magnetization reversal mechanisms (nucleation, domain boundary displacement). In this work, a correlation is established between magnetic characteristics of permanent magnets (Y25 and AlNiCo) and the fractal dimension of magneto-optical images of their stray fields. Bismuth-containing ferrite-garnet films were used as an indicator. It is shown that the limiting values of the fractal dimension: 1,76 for a ferrite magnet and 1,85 for an AlNiCo magnet, are consistent with the results obtained for NdFeB (grade N35) and SmCo (grade KC37) magnets, as is the behavior of the field dependence of the fractal dimension. The behavior of the field dependence of magnetization Mmo(Hrev) has similar features to a similar dependence recorded for a permanent magnet NdFeB (grade N35), but the values of the demagnetizing fields for the Y25 sample are much smaller. The paper discusses the relationship between the mechanisms of magnetization reversal of permanent magnets and the behavior of the Mmo(Hrev) dependence.

The paper presents the results of an experimental study of the dielectric and switching characteristics of some initial and annealed alanine-doped crystals of the triglycine sulfate group at room temperature. The results of measurements and calculations of the effective permittivity, switchable polarization, coercive and bias fields, unipolarity coefficient and dielectric loss tangent are presented. It was found that for most samples before and after annealing, the dielectric hysteresis loops are unipolar and shifted along the abscissa axis. This indicates a preferential orientation of domains and the presence of bias fields. As a result of annealing, the values of the coercive field and the unipolarity coefficient of the crystals decrease, and the switchable polarization increases. It is shown that the field dependences of the effective permittivity of the crystals before annealing have extrema lying in the field range of (5-7,5) center dot 104 V center dot m-1 and in the range (5-12) center dot 104 V center dot m-1 after their annealing.

The results of experimental studies of magnetic properties and magnetization reversal processes of a series of alloys Sm-Gd-Zr-Co-Cu-Fe are presented. The studied samples were subjected to prolonged isothermal annealing for 24 hours, which made it possible to achieve the formation of a certain nanostructure that affects the hysteresis properties of the material and allows to achieve a high coercivity state. According to the magnetic measurements data obtained by the method of a vibrating magnetometer, the hysteresis loops are constructed, the dependence of the saturation magnetization, and the coercive force on chemical composition, and the values of the temperature coefficient of magnetization change depending on the relative content of Sm and Gd are determined. It is shown that the substitution of a part of samarium atoms for gadolinium atoms increases the effect of the mechanism of irreversible rotation of the spontaneous magnetization vector on the remagnetization of samples. Application of the studied samples in various devices puts serious demands on the stability of their magnetic properties at high temperatures. Our researches allow us to conclude that compounds with gadolinium concentration x=0,5 have the greatest coercive force, and compounds with gadolinium concentration in the range x=0,5-0,6 have the highest temperature stability.

Results are presented from a fractal analysis of images of the surface of a KC-37 permanent magnet, obtained via the polar Kerr effect using an indicator bismuth-containing ferrite-garnet film after magnetization reversal by a pulsed field of 0.1–1.5 T. The obtained dependences of the residual magnetization on the magnitude of the external pulsed field are compared to the fractal dimension of magneto-optical images of the magnet’s surface after exposure to the pulsed field. It is shown that the maximum value of the fractal dimension corresponds to the demagnetized state of the magnet.