Magnetic anisotropy and domain patterning of amorphous films by He-ion irradiation

The magnetic anisotropy in amorphous soft magnetic FeCoSiB films was modified by He-ion irradiation. A rotation of uniaxial anisotropy depending on the applied field direction in the irradiated areas is observed by magnetometry and complementary domain observation by Kerr microscopy. No significant degradation in magnetic properties relative to the as-deposited state is found from the magnetization loops on nonpatterned films. Using irradiation together with photolithography, the films were treated locally, resulting in "anisotropy patterned" structures. Complicated periodic domain patterns form due to the locally varying anisotropy distribution. Overall magnetic properties and domain patterns are adjusted.