Rf-sputter deposition was applied to investigate a possibility to obtain ferromagnetic Fe-Ni thin films having different coercivity for ferromagnetic layers in magnetic spin tunneling junction. Two kinds of targets were used in the deposition applying rf-power in a range up to 250 W; a composite target where Ni chips of 1 × 1 cm
2 were distributed on an Fe target of 3 in diameter in 25% in area ratio, and a 75Fe-25Ni alloy target. The deposited thin films were more Ni rich than the target compositions due to different sputtering rates between Fe and Ni. The films were γ-(Fe, Ni) with Ni 40-55 at% composition in the usage of the former target and α-(Fe, Ni) with Ni 30-40 at% composition in the latter target. The latter films had large magnetization values of about 200 emu/g. They were metastable and converted to γ-(Fe, Ni) above 600 K. There was an enough coercivity difference between 55 Oe for the thin film prepared applying rf-power of 100 W and 30 Oe for the film prepared at 250 W using the alloy target.
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