Coexistence of magnetic domains with in-plane and out-of-plane anisotropy in a single GaMnAs film

Magnetic anisotropy of the ferromagnetic semiconductor GaMnAs film grown on a (001) GaAs substrate was investigated by using Hall effect and magnetization measurements. When field strength was swept at a fixed direction in the film plane, abrupt transitions in the Hall resistance appeared while reducing the field strength even before the field direction is reversed. We show that this phenomenon is related to the presence of magnetic domains with a vertical easy axis in the film, as identified via Hall measurements performed with a field applied normal to the plane. The coexistence of magnetic domains with both in-pane and out-of-plane anisotropies in a single film was further confirmed by direct measurement of the corresponding magnetization components of the film.