Magnetic Anisotropy In Epitaxial InMnAs

The magnetic anisotropy of epitaxial InMnAs thin films have been studied using the longitudinal magneto-optical Kerr effect and magnetic force microscopy at room temperature. Square hysteresis loops were obtained for phase pure layers grown on InAs and GaAs substrates. InMnAs layers on GaAs possess magnetic in-plane isotropy as evidenced by hysteresis loops that were independent of in-plane rotations. On the other hand, InMnAs layers on InAs exhibit strong two-fold in-plane anisotropy. The easy axis of magnetization is along the [110] and [0] directions. In addition in-plane elliptical domains predominantly aligned along the easy axis were observed by magnetic force microscopy. The observed uniaxial in-plane anisotropy is attributed to the presence of unrelaxed coherency strain in InMnAs films grown on InAs.