This paper presents the results of an investigation of changes in the structure, magnetic, electrical, and thermal properties of a nanostructured bismuth ferrite powder prepared by the combustion of nitrateorganic precursors before and after heat treatment at temperatures of 500, 600, 700, and 800°C. It has been shown that there is a dependence of the magnetic properties on the dispersion of the particles. The specific features of the temperature and frequency dependences of the dielectric properties over wide ranges of frequencies and temperatures, as well as near the Néel temperature, have been considered.

The effect of quenching conditions on the mechanical and magnetic properties of a meltquenched wire with a core diameter of 50 μm, which is made of a model soft magnetic Co 69 Fe 4 Cr 4 Si 12 B 11 alloy and is fabricated by the Ulitovskii-Taylor method, is studied. The highest set of mechanical and soft magnetic properties of a wire is achieved when it is quenched from the upper position of a quenching stream. The lowering of the position of the quenching stream degrades the mechanical and magnetic properties of the wire at a retained amorphous structure in it.

The magnetic properties of initial and heat-treated Co 69 Fe 4 Cr 4 Si 12 B 11 microwires in a glass shell with the diameter D = 125 μm and the diameter of the amorphous metallic core d = 90 μm produced by the Ulitovsky-Taylor method have been studied. It has been found that the magnetic characteristics, in particular, the saturation field H S and the coercive force H C of the samples annealed at a temperature T < 300°C do not differ from H S and H C of the initial microwire, and those of the samples annealed at T ≥ 400°C increase by almost one order of magnitude. The obtained experimental data have been explained by the structural features of the microwires. The near-surface values of H S and H C at T < 300°C are found to be larger than the bulk values by a factor of 5–10. These experimental data have been explained by the existence of structural and chemical ingomogeneities in the near-surface layer, which are inherent in amorphous materials. This difference decreases with a further increase in the annealing temperature, but H S and H C increase substantially. This fact has been explained by the beginning of the microwire crystallization.

The preparation conditions and the magnitudes of the uniaxial and unidirectional magnetic anisotropies of IrMn/Co structures with an alternative sequence of deposition of antiferromagnetic and ferromagnetic layers upon heat treatment and cooling in an external magnetic field have been investigated. It has been revealed that the unidirectional anisotropy (exchange bias) arises in the structure with an antiferromagnetic layer deposited on a ferromagnetic layer (TS structure) at an annealing temperature of higher than 100°C. In structures with a ferromagnetic layer deposited on an antiferromagnetic layer (BS structure), the exchange bias does not arise in the annealing temperature range under investigation. The possible factors responsible for this effect and the ratio between the temperature of the appearance of the exchange bias and the Néel temperature have been discussed.

Thin ferromagnetic films with in-plane magnetic anisotropy are promising materials for obtaining high microwave permeability. To produce a bulk massive sample from thin films, multi-layer films made of a number of many thin films may be used. The paper reports on an experimental study of microwave and static magnetic properties of multi-layer iron-based films and composite samples made of these. The multi-layer films under study are deposited onto a mylar substrate by a magnetron-sputtering process performed in Ar atmosphere with controlled N2 admixture. The sputtered iron layers are alternated with SiO2 layers. The measured static and microwave magnetic properties of the bulk sample are found to differ from the properties of constituent films. This is an evidence for strong interactions between the magnetic layers in the sample, which interact at distances exceeding greatly the distance between adjacent magnetic layers. A theoretic model is developed to account for magneto-dipole interactions between iron films in a multi-layer system. The model explains the anomalously high demagnetization field of the sample observed in the measurements.

Multilayered composites consisting of many thin ferromagnetic films with in-plane magnetic anisotropy separated by non-magnetic dielectric layers of different sizes are experimentally and theoretically investigated. Thin samples as well samples with transverse sizes comparable with longitudinal ones are used. The measured static magnetic properties of the bulk sample are found to be different from the properties of constituent thin films. This is an evidence for strong interactions between the magnetic layers in the sample, which interact at distances exceeding greatly the distance between adjacent magnetic layers. A theoretic model is developed taking into account magneto-dipole interactions between iron films in a multi-layer system. The model explains the anomalously high demagnetization field of the sample observed in the measurements.

The influence of the glass-cover thickness on the magnetoimpedance of amorphous cobalt-based microwires is studied. Microwires with different values of the glass thickness were obtained by etching off the glass cover with fluorhydric acid. It was found that, as the cover thickness decreases, the magnetoimpedance ratio does not substantially change, while the intensity of the external magnetic field in which the impedance attains its maximum also decreases. The experimental results are explained using a model taking into account changes in the radial distribution of the anisotropy axes with a decrease in the glass-cover thickness.

The effect of glass coating thickness on the magneto impedance in Co-based amorphous microwires was studied. The microwires with different thickness of the glass layer were obtained by means of etching in hydrofluoric acid solution. It was observed that the value of the external magnetic field corresponding to the maximum of the impedance decreased with the thickness of the glass layer, whereas the magneto impedance ratio did not change significantly. The experimental results are interpreted in terms of changes in the radial distribution of the easy magnetization axes.

We have studied the response voltage in a coil wound on a glass-coated amorphous microwire, through which an ac current is passed. The amplitudes of the first and second harmonics of the response voltage have been studied as functions of the applied magnetic field. The first harmonic amplitude, which corresponds to a linear off-diagonal magnetoimpedance, is negligibly small, while the second harmonic is highly sensitive to the magnetic field. The behavior of harmonics in the frequency spectrum of the response voltage can be explained by the existence of a regular domain structure in the surface layer of the microwire exposed to a weak magnetic field.

The off-diagonal magnetoimpedance in glass-coated Co-based amorphous microwires is studied using a pick-up coil wound around the sample. The first and second harmonics in the pick-up coil voltage were measured as a function of the external magnetic field. It was observed that the first harmonic in the voltage corresponding to the linear off-diagonal magnetoimpedance was very small. This fact is attributed to the existence of the regular bamboo domain structure within a surface layer of the microwire. On the contrary, the second harmonic in the voltage differed from zero, which is related to the domain-walls motion.

Domain walls in Co-based amorphous microwires with high-frequency current are investigated by the magnetoimpedance measurements. Dynamic stray fields of magnetic charges on domain walls were found out. In frame of the Landau–Lifshits approach the influence of the magnetic charges interactions on the microwire magnetoimpedance is studied. Parameter describing lowering of the magnetoimpedance is obtained.