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 2–1422–142 monolayers (ML) grown on {4×2}{4×2} reconstructed InAs(0 0 1) was investigated by in situ   ferromagnetic resonance. The easy magnetization direction was found to be parallel to the [11¯0]-direction for Fe films below 4 ML, while it rotates by 45∘45∘ toward the [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 〈11¯0〉-directions in contrast to the volume contribution which favors easy axes along the 〈110〉-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 22 up to 142142 ML.