Fe monolayers on InAs(0 0 1): An in situ study of surface, interface and volume magnetic anisotropy

The magnetic anisotropy of epitaxial Fe films with thicknesses in the range of 22142 monolayers (ML) grown on f4 � 2g reconstructed InAs(0 0 1) was investigated by in situ ferromagnetic resonance. The easy magnetization direction was found to be parallel to the ½1 10 � -direction for Fe films below 4 ML, while it rotates by 45 � toward the ½ 100 � -direction. It is observed that both surface-interface and volume contribution to the perpendicular anisotropy favor an easy axis perpendicular to the film plane. The cubic surface-interface anisotropy is relatively large with easy axes along h1 10 i-directions in contrast to the volume contribution which favors easy axes along the h 110 i-directions. The volume contribution is found to be larger than the Fe bulk cubic anisotropy. A thickness independent uniaxial anisotropy has been found in films with a thickness of 2 up to 142 ML.