The role of thermal scattering in spin-dependent transport of hot electrons at 0.9 eV is studied using a spin-valve transistor with a soft Ni(80)Fe(20)/Au/Co base. Spin-dependent scattering makes the collected electron current depend sensitively on the magnetic state of the base. The magnetocurrent reaches 560% at 100 K, decays with increasing temperature, and a huge effect of 350% still remains at room temperature. The results demonstrate that thermal spin waves produce quasielastic spin-flip scattering of hot electrons, resulting in mixing of the two spin channels.

Abstract4oNilPt multilayers were prepared by magnetron sputtering using Ar gas. Effects of Pt seedlayer and Ar sputtering pressure on magnetic and structural properties are investigated. Microstructures of multilayers were analysed using XRD and TEM. It was found that perpendicular magnetic anisotropy and coercivity increase with increasing either the thickness of Pt seedlayer or Ar pressure. The causes of increases in perpendicular anisotropy and coercivity are discussed in relation to the interface roughness, the curvature of layers and the columnar structures.

The magneto-optical Kerr rotation (0,) spectra and the related properties have been measured in ordered and disordered phases of several kinds of Fe-R alloy films. The / 0, 1 in as-deposited (disordered) films becomes gradually larger with increasing Fe content until about SO at% Fe, but the shape of 0 k spectra does not change so much. After annealing, however, all the 0, spectra were changed. A considerable change of the Ok spectra near 300 nm. which would be expected by the anti-parallel alirhment of the polarized Pt soins to Fe spins after annealing. was not ohserved in the films with _ approx. 50 at? Fe.

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Pulsed laser ablation (PLA) has been used to grow barium ferrite films on AlzQ3 single crystal substrates. When deposition occurs in an oxidising atmosphere at high temperatures, the films are single BaFelz019 phase with very well orientation following the (001) texture, and exhibit a large perpendicular magnetic anisotropy. In this case, the microstructure and the anisotropy orientation are not influenced by variation of the oxygen pressure in the range 20-530 mtorr, but the coercivity and the remanence are affected. Films prepared without oxygen, are isotropic. XRD measurements reveal the absence of the BaFelzQp~ which becomes unstable. On the other hand, the presence of other phases as Ba2FehO1l and Fez03 is detected. The annealing study reveals the presence of the threshold temperature (620°C) for the appearance of the magnetisation and the anisotropy orientation. This temperature also corresponds to the onset in growth of the crystalline structure of barium ferrite. In the latter case, the coercivity was found to be greatly reduced by the increase in grain size at higher annealing tempera turesZndex T e r m -Ba -Ferrite, Laser Ablation, Perpendicular Anisotropy, Annealing