Solid State Phenomena Vols. 152-153

Abstract: Thin films of amorphous FeCuSiNbB alloy have been deposited by RF sputtering with various deposition rates. The bulk oxygen content has been characterized using EDS and XPS. Its dependence on deposition rate shows that water vapour in the sputtering chamber is at the origin of the contamination. It allows also estimating the adsorption coefficient of the oxygen on the sample to be around 15 % at 350 K. The magnetic hardness and the resistivity increase with the contamination in oxygen. In devitrified films, this increase is also related to an enrichment of the residual amorphous matrix in oxygen.

Abstract: In this work, the structural and magnetic properties of single-phase TbxDyyHoz(Fe,Co)2 (x + y + z = 1) alloys have been investigated by means of X-ray diffraction, 57Fe Mossbauer spectroscopy, magnetization measurements and a standard strain gage technique. The magnetostriction of TbxDyyHoz(Fe,Co)2 was examined against an applied magnetic field up to 10 kOe in 80 - 400 K temperature range. The Co-containing compounds are found to have high values of magnetostrictive susceptibility due to compensation of magnetic anisotropy in both the rare-earth and 3d transition metals sublattices.

Abstract: High coercive garnet-ferrite films are being synthesized for thermo-magnetic recording, for example, by focused laser beams. These films can be characterized by a couple of parameters very suitable for recording reconfigurable magnetic atomic traps whose geometry is visible. On the other hand, slightly other films can be used for contact printing of high density and weak residual magnetization records in criminalistics. Both types are investigated experimentally in this work.

Abstract: The results of magnetometric, Mössbauer and XMCD (X-ray Magnetic Circular Dichroism) studies of B2 or DO3–type ordered (25 to 35 at.%Al) and disordered by mechanical activation (35 to 60 at.% Al) Fe-Al alloys are considered. For the description of magnetic characteristics of the studied alloys the validity of local magnetic moments models is discussed. The models suppose that Fe atom local magnetic moments are collinear with magnitude and direction depending on the number of Al atoms in the Fe nearest neighbourhood.

Abstract: In this paper we have studied from first-principles the effect of magnetism on the hydrogen-metal interaction and the binding properties of palladium with 3d-alloying atoms in the presence of vacancies induced during hydrogenation process. Our first-principles calculations were carried out by means of state of the art ab-initio method based on density functional theory and all-electron PAW-potentials. We have analyzed the changes of the atomic and electronic structures of palladium crystal induced by the presence of substitutional 3d-alloying atoms, interstitial hydrogen and structural defect (palladium vacancy). The obtained results have shown that magnetism can strongly affect the hydrogen-metal interaction in palladium based alloys. We have also demonstrated that the presence of vacancies in the palladium matrix can alter the interaction energy between hydrogen and alloying transition metal atoms.

Abstract: Solid phase high energy mechanochemical interaction of α-Fe2O3(hematite) and Fe in powder mixture have been studied. The formation of amorphous iron-based magnetic phase in this process was detected by means of Mossbauer spectroscopy and magnetic measurements. The amount of this phase increases with Fe addition in reduced mixture. Its thermal stability have been studied by magnetic and DCS measurements at constant α-Fe2O3 and gradually increased Fe concentrations.

Abstract: Specially picked up web-chamber is used for visualization of domain structure in hematite. An analysis of domain configuration shows, that domain structure of hematite in a basal plane represents multilayered structure which contains domains both in paralleled thickness and in the parallel basal planes. The temperature features of magnetic permeability and domain structures in Fe2O3:Ga crystals near the Morin transition are investigated. Observable changes of magnetic permeability and changes in domain structure confirm that transition from АFM to WFM occurs in the hematite with Ga impurity as transition of the first sort. Results of research of antiferromagnetic and weakly ferromagnetic resonances (AFMR and WFMR) in these compounds are presented.

Abstract: Temperature dependences of the lattice parameters, magnetization and magnetic susceptibility have been measured for the ErFe2Hx hydrides with different hydrogen content x and for the ErFe2D3.1 deuteride. For the samples with a hydrogen content of about 3.1, structural transition from the cubic to the rhombohedral phase has been observed in the temperature range 280 – 310 K. Small variation of hydrogen content does not shift the transition temperature, but influences the amount of the low-temperature rhombohedral phase. The temperature dependence of magnetization shows up an anomaly in the range of the phase transition, which is due to the difference in the magnitudes of magnetic moments and exchange interactions in two phases. Structural and magnetic studies point to a diffusion nature of the phase transition. Upon heating the samples in vacuum there takes place decomposition of the hydride. The hydride with x = 1.6 which forms at the intermediate stage of decomposition possesses an ordering temperature higher than that for the parent ErFe2 compound.