Guidelines for attaining optimal soft magnetic properties in FeAlSi films

Abstract

Nm-order FeAlSi epitaxial films with a partially D03-ordered structure were grown on MgO substrates, and ideal soft magnetic properties were obtained. We found that the sign of the magnetocrystalline anisotropy constant K1 changes with increasing annealing temperature for certain FeAlSi compositions. This is caused by a change in the volume balance of the ordered phases with the annealing process and the point at which K1 ∼ 0 shifts to the Al-rich concentration as the degree of D03-ordering decreases. K1 was precisely measured by ferromagnetic resonance under the optimal condition, and the value of 1.6 × 102 (erg/cc) was obtained, which is comparable to that of bulk. The uniaxial component of the magnetic anisotropy due to magnetostriction was small, and a fourfold symmetric component due to magnetocrystalline anisotropy was dominant.