Solid State Phenomena Vol. 215

Abstract: The longitudinal ρ_xx(B) and Hall ρ_xy(B) magnetoresistances are investigated in the integer quantum Hall effect regime in n-InGaAs/GaAs double quantum well nanostructures in the magnetic fields B up to 16 T at temperatures T = (0.05-4.2) K before and after IR illumination. The analysis of the quantum Hall effect plateau-plateau transitions based on the scaling hypothesis with regard to electron-electron interaction was carried out.

Abstract: Co and Ni nanoparticles were fabricated in fused silica plates by ion implantation technique. Electron microscopy showed the nanoparticles to be of spherical shape. Magnetic circular dichroism (MCD) was investigated in the spectral range 1.2 - 4.2 eV in a field of about 3 kOe. MCD spectra are considerably different from the spectra of thin nickel and cobalt films. MCD spectra for Ni nanoparticles are associated with surface plasmon resonance.

Abstract: The Al₂O₃-FePd₃ structure was fabricated by aluminothermy, or the Goldschmidt reaction. The initial structure was prepared by the formation of a highly-ordered L1₀-FePd epitaxial film with the use of the solid-state reaction in a Fe(001)/Pd(001) bilayer system on the MgO substrate. To obtain a granular structure, the L1₀-FePd samples were oxidized in air with the subsequent deposition of an aluminum layer onto their surface and vacuum annealing. Depending on annealing time and temperature, a system of L1₂-FePd₃ grains 5 nm in size was formed in an Al₂O₃ insulating matrix. Parameters of thermal treatment of the initial structure are presented, the occurring phase transformations are described, and the magnetic characteristics are measured. It is established that the ordered L1₀-FePd phase is obtained at an initiation temperature of the reaction of about 450 ^оС and the granular L1₂-FePd₃ system forms at 600-650 °С.

Abstract: Using the scanning spectrometer of ferromagnetic resonance it was found that the small deviation of the incidence atoms from the normal during the deposition had a strong influence on magnetic parameters of thin films.

Abstract: Within the frame of average spin the dependence of Neel temperature of ultrathin antiferromagnetic film for FCC crystalline lattice on its thickness and the concentration of magnetic atoms has been defined. The λ values calculated by us are close to experimental values obtained for the films СoO/SiO2. The increasing of thickness leads to decreasing of the critical concentration down to the value equal to percolation threshold.

Abstract: Using the scanning spectrometer of ferromagnetic resonance (FMR) the experimental dependences of the resonance field and FMR line width of thin permalloy magnetic films, which were deposited in vacuum on the substrate with an artificial texture, were obtained. The texture was produced by putting parallel grooves using a diamond cutter on glass substrates with period from 5 to 100 μm. It was found that the presence of the texture led to a considerable increase of the resonance field and FMR line width, when the external field was directed orthogonal to the grooves. On the base of a numerical micromagnetic simulation the explanation of the nature of observable in thin magnetic films effects was given.

Abstract: The deposition kinetics, structure and magnetic properties of electroless deposited films Ni-P were investigated depending on the amount of sodium hypophosphite in the electroless bath. It was found that the film deposition rate is linear and unambiguously varies with the hypophosphite content from 2 to 13 g/l and from 23 to 25 g/l. The deposition rate varies widely in the hypophosphite concentration range from 13 to 23 g/l. The films are composed of amorphous Ni-P phase and fcc Ni-P solid solution with phosphorus content from 1 to 4 at.% P according to X-ray diffraction. The partial amount of amorphous phase is increased with concentration of sodium hypophosphite. The ferromagnetic resonance field is independent on the concentration of sodium hypophosphite, which assumes to be result from the laminated allocation of the amorphous and fcc phases in the film.

Abstract: Phase composition, crystal structure and magnetic properties of ordering FePd and Fe₅₀Pd_50-xPt_x (х = 1-10 atomic %) alloy films were studied. Spectral dependencies of Faraday rotation and optical absorption were measured. We studied how thermal treatment affects crystal structure, magnetization and coercive force in ordered alloys and how the degree of atomic order affects the value of perpendicular magnetic anisotropy. It was shown that near equiatomic ordered FePd and Fe₅₀Pd_50-xPt_x (х = 1-10 at. %) alloy films can be used as medium for magnetic and thermo-magnetic data recording.

Abstract: The peculiarities of domain structures (DS) have been investigated in the two-layer film of (YGdTm)₃(FeGa)₅O₁₂/(YEu)₃(FeGa)₅O₁₂ composition with a magnetic compensation point (T_C) in one of the layers and in the single-layer witnesses-films. It is shown that a change in the ratio of energies of magnetostatic and exchange interactions between the layers under temperature change induces a phase transition (PT) in the domain structure and a spin-reorientation phase transition (SRPT).

Abstract: The mechanism of spin-reorientation phase transmission (SRPT) has been examined. The structure change of domain boundaries in process of phase transmission (PT) has been researched. The models of domain structure (DS) relevant to experiment have been offered. It is shown that in connection with temperature change of the anisotropy constants the structure of domain boundaries and view of DS changes as well, SPRT and PT takes place in the domain boundaries.