パルス電気めっきCo-Cuグラニュラー合金膜のGMR効果と磁気特性に対する熱処理効果  [in Japanese] Effect of Annealing on the Giant Magnetoresistance and Magnetic Properties of Pulse-Electroplated Co-Cu Granular Alloy Films  [in Japanese]

Granular alloy films Co_xCu_<1-x> (0.17≦x≦0.66) were prepared by pulse plating. Although a second phase, probably hexagonal close-packed phase, was present in the X-ray diffraction pattern for all samples examined, the matrices showed the face-centered cubic lattice parameter decreasing almost linearly with increasing x. The magnetoresistance (MR) of films was found to be larger after annealing at an appropriate temperature between 400℃ and 600℃. A maximum value of the MR ratio of about 4.2% was observed at the composition around x=0.2. The remanence ratio was found to be 0.4-0.6 for all films measured, indicating the presence of ferromagnetically interacting particles even in the as-deposited condition and to depend little on the composition. The average size of magnetic particle D for x=0.31 estimated using M(H) data at room temperature was found to be about 9.7nm before annealing and 12nm after annealing at 450℃. The large magnetic particle size in the as-deposited state seems to be the main cause of the small MR value.