Guidelines for attaining optimal soft magnetic properties in FeAlSi films

Nm-order FeAlSi epitaxial films with a partially D0(3)-ordered structure were grown on MgO substrates, and ideal soft magnetic properties were obtained. We found that the sign of the magnetocrystalline anisotropy constant K-1 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 K-1 & SIM; 0 shifts to the Al-rich concentration as the degree of D0(3)-ordering decreases. K-1 was precisely measured by ferromagnetic resonance under the optimal condition, and the value of 1.6 x 10(2) (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. (C) 2022 Author(s)