数nm膜厚のパーマロイ薄膜の誘導磁気異方性

概要

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The induced anisotropy in thin Ni_<79>Fe_<21> films was investigated. The value of the induced anisotropy field H_k was found to decrease as the film thickness decreased, particularly below 20 nm, even after an adequate annealing procedure with a magnetic field. The value of H_k at 3 nm was found to be nearly half that at 200 nm. Almost the same thickness dependence of H_k was found to exist in both Ni_<77>Fe_<23> and Ni_<81>Fe_<19> films, except for slight differences in the absolute magnitude of H_k, depending on the composition. A series of CoZrNb amorphous films showed a qualitatively similar thickness dependence of H_k. On the other hand, the easy axis of the Ni_<79>Fe_<21> films thinner than 20 nm was switched to the field direction by annealing with a magnetic field perpendicular to the easy axis of the as-deposited films, even at a low annealing temperature of 220℃. The absolute values of H_k in the 3 and 5 nm films after annealing were nearly as large as in the as-deposited films. It is likely that the rearrangement of atom pairs can easily occur in the surface region, resulting in the switching of the easy axis to the annealing field direction in very thin films.
2000-04-15