I. V. Zolotukhin

Low temperature behaviour of the giant magnetoresistivity in CoFeB–SiOn granular composites

Giant magnetoresistivity (GMR) at different temperatures as well as magnetization processes were studied in amorphous granular composites (Co41Fe39B20)x (SiOn)100−x over a wide concentration range (20 ≤ x, at. % ≤ 59). Magnetoresistivity of the composites with large dielectric content (below a percolation threshold) is enhanced on cooling down to 77 K and reaches 7% in (Co41Fe39B20)30 (SiOn)70. The observed GMR enhancement directly correlates with the rise of the relative change of the composites magnetization ([m77 − m300 ]/m300) occurring on temperature reduction. The temperature dependence of the composites GMR exhibits a clear maximum in the vicinity of 77 K if a wider temperature range (2–300 K) is considered. The difference between the GMR values measured at 77 and 2 K is one order of magnitude. Strong Coulomb blockade is observed in this composite at low temperature.

Inverse magnetoresistance in (FeCoB)-(Al2O3) magnetic granular composites

The magnetoresistance, magnetization, and microstructure of granular composites with the general formula (Fe40Co40B20)x(Al2O3)100−x were studied for contents of the amorphous metallic component both above and below the percolation threshold (x≈43). The low-temperature transverse magnetoresistance of the composites is negative at x=41 and practically zero for x=49. For metal contents below the percolation threshold (x=31), a noticeable (7–8%) positive magnetoresistance, reached in magnetic fields of about 17 kOe, was observed. Possible mechanisms of the generation of inverse (positive) magnetoresistance are discussed.

Anomalous magnetization processes in the amorphous compensated Tb21Co79 alloy

Abstract Magnetic properties of amorphous TbxCo100-x alloys with an induced in-plane uniaxial anisotropy were studied. Complex reorientation transitions, not observed earlier in amorphous materials, were found. These transitions were most vivid in Tb21Co79 amorphous alloy, in which at low temperatures the resulting moments of Tb and Co sublattices practically compensate one another.

The effect of hydrogen on the electric conductivity of tin oxide doped with yttrium

Amorphous films of tin oxide doped with yttrium were obtained by ion beam sputter deposition. After crystallization, the films acquired a nanocrystalline structure. The introduction of yttrium leads to an increase in the crystallization temperature of tin oxide. The electric conductivity of films containing yttrium in excess of 1 at. % is highly sensitive to hydrogen. Nanocrystalline films of tin oxide doped with yttrium may serve as hydrogen-sensitive media.

Hydrogenation effect on magnetic properties ofhydrided REM-3D amorphous alloys

Abstract The pressure effect on magnetic properties of amorphous rare-earth basedalloys and their hydrides was investigated for the temperatures close to phase transition to spinglass like state point. It was established that the pressure decreases the temperature of transition,otherwise hydriding makes the temperature higher. Experimental results are explained by meansof strong dependence of exchange integrals on interatomic distances.