Sonochemically prepared Pt, Au and Pd nanoparticles were successfully immobilized onto TiO2 with the assistance of prolonged sonication. Their photocatalytic activities were evaluated in H2 production from aqueous ethanol solutions. Beside the sonochemical method, the conventional impregnation method was also employed to prepare photocatalysts. The sonochemically prepared catalysts showed higher activities than did the conventional ones. Their photocatalytic activities depended on the work functions and the dimensions of supported noble metal nanoparticles. Smaller Pt nanoparticles effectively restricted recombination of electrons and holes and provided H2 at a higher rate.

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Aqueous sample solutions containing noble metal ions (HAuCl4, Na2PdCl4, H2PtCl6), polyethyleneglycol monostearate, and magnetic maghemite nanoparticles were irradiated with high power ultrasound. Analyses of the products showed that noble metal ions were reduced by the effects of ultrasound, and the formed noble metal nanoparticles were uniformly immobilized on the surface of the maghemite. The present "one pot process" significantly simplifies the immobilization of noble metal nanoparticles on the surface of supports, compared with the conventional impregnation method. The average diameter of immobilized Au was 7-13 nm, and the diameters of Pd and Pt were several nm. The diameters depended upon the concentration of polyethyleneglycol monostearate and the concentration of noble metal ions, but not upon the maghemite concentration, indicating the possibility of the morphological controls of the products by adjusting these preparation conditions. The measurements of the average diameters and the numbers of immobilized Au nanoparticles obtained under various conditions suggest that the nucleation of Au does not occur on the surface of maghemite, but it might occur in the homogeneous bulk solution.

Current-perpendicular-to-plane junctions with different cross-sectional areas were fabricated from Fe3Si/FeSi2 artificial lattice films, wherein antiferromagnetic interlayer coupling was induced across the FeSi2 spacer layers, by employing a focused ion beam (FIB) apparatus. Evident hysteresis loops in the electrical resistance for current injection due to current-induced magnetization switching (CIMS) were observed. The average value of critical current densities for inducing CIMS was 2  10 2 A/cm 2 , which is at least three orders of magnitude smaller than values that have ever been reported. This might be because CIMS in our junctions is induced by the destruction of the AF interlayer coupling, which differs from the general mechanism of CIMS.

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