極薄軟磁製薄膜の誘導 : 軸磁気異方性

概要

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The induced uniaxial anisotropy field H_k in very thin permalloy films, sandwiched by seed and protective Ta and Cu layers, was investigated. The value of H_k of the Ta/Cu/ Ni_<79>Fe_<21>/Cu/Ta films was found to decrease as the film thickness decreases below 20 nm, even after an annealing procedure in a magnetic field. This H_k reduction is similar to that of Ta/Ni_<79>Fe_<21>/Ta films, indicating that the H_k reduction is independent of the surface energy or crystal structure of the seed and protective layers. Thickness dependence of film magnetostriction λ_<p-p> of these films did not show any clear correlation with that of H_k, indicating that the H_k reduction is not simply caused by the magnetostrictive effect a thin films. The higher mobility of surface atoms may disrupt the alignment of atom-pairs parallel to the field direction during film deposition and annealing, resulting in the smaller induced anisotropy of very thin films.
2001-04-15