Papers by Author: S.V. Komogortsev

Abstract: The morphology and magnetic characterization results of electroless deposited CoP coating on the copper microgrid with the mesh size of 50 microns are presented and discussed. The deposited coating is found to be well uniform by the thickness. Magnetic anisotropy in the plane of the grid has been studied by the hysteresis loops and the FMR spectra and discussed with the modeling of the grid as the frame grid system of magnetic tubes.

Abstract: The effect of the atomic disorderorder transformation on remanence, coercivity and magnetic anisotropy energy in CoPt nanoparticles prepared by thermal decomposition and annealed at 400°C for 4 and 16 hours has been studied. The observed remanence and magnetic anisotropy energy enhancement versus annealing time are discussed in the terms of ordering domain formation inside nanoparticles.

Abstract: The quantitative analysis of static ferromagnetic correlations in nanocrystalline films Fe₇₈Zr₁₀N₁₂ was performed by two methods: the correlation magnetometry technique and magnetic force microscopy. The data, obtained by both methods, prove to be in good agreement.

Abstract: Powders of Ñî-Ð alloy with ultradispersed corundum (Al₂O₃) and detonation nanodiamond (DND) precipitates were synthesized by chemical reduction. The products were characterized by X-ray diffraction and scanning electronic microscopy. The shape of the particles was spherical and they were ferromagnetic. Magnetization dependence on field in applied fields of up to 40 kOe and magnetization dependence on temperature in the temperature range from 2 to 300 K were measured. Influence of precipitates on magnetic properties was studied.

Abstract: The magnetization correlation function for two-phase one-dimentional chain of the ferromagnetic exchange-coupled nanoparticles with a random anisotropy was calculated. The dependence of the magnetic correlation radius and the average magnetic anisotropy constant on the intrinsic size of the phase inhomogeneity was founded. The data allows estimating the applicability limits of the analytical equations for the magnetization curves approaching saturation of two-phase ferromagnetic nanomaterials.

Abstract: In the paper, we will present experimental results on the Fe73.5CuNb3Si13.5B9 ferromagnetic resonance (FMR) line width as a function of annealing conditions, as well as the annealing-temperature dependence of the crystallite size, coercive force, and the magnetic anisotropy field. We shall show the interrelationship of these quantities, demonstrate that these parameters are all traceable to the nanoparticle crystallization, and indicate how they can be examined by extending the random anisotropy theory. To obtain quantitative parameters of random magnetic anisotropy we investigate the magnetization curves approaching saturation. This technique allows one to quantitatively determine the local magnetic anisotropy field (Ha) and magnetic anisotropy correlation radius (Rc), as well as to estimate the averaged magnetic anisotropy field (L) and ferromagnetic correlation radius (RL).

Abstract: The properties of Co-SiO2 nanogranular composite films, containing a Co volume fraction ranging from 0.3 to 0.8, have been characterized by means of magnetic measurements, NMR study, and ferromagnetic resonance. Thermal decrease of CoX(SiO2)100-X magnetization follows the T3/2 law and allows to estimate the exchange interaction constant A. With growing nominal Co content the transitions from granular to continuous structural state at 36% Co are registered by FMR measurements. The spectrum of standing spin-wave has been detected in the perpendicular experiment configuration for films with the Co content above 52 vol. %. It is found that the type of the dispersion relation of spin waves in Co-SiO2 composite films is affected by the exchange coupling fluctuations.

Abstract: Solid-state synthesis of a Sm2Co7 (110) hard magnetic phase prepared by successive deposition of Co and Sm layers onto a MgO(001) surface at a temperature of 400 С has been experimentally studied. Upon annealing at 500 С, the structure of the material changes, which leads to the formation of an epitaxial Sm2Co17 (110) phase. The first and second magnetocrystalline anisotropy constants of the Co-Sm have been determined.

Abstract: Data on the random magnetic anisotropy and exchange correlation length in soft magnetic nanocrystalline Fe79Zr10N11 films were obtained using a calculation technique in frame of the random magnetic anisotropy model. The calculations are performed using approach magnetization to saturation curves. The local magnetic anisotropy fields (Ha), and magnetic anisotropy correlation radii (Rс) reduced to =(A/K)1/2 were determined for the films annealed at 475 and 6000 C for 0.5, 1, 2, and 3 h. The correlation Hc ~(Rc/)3 for the all annealed films was found.