Magnetization reversal behavior of GaMnAs film grown on Si substrate investigated by planar Hall measurements

Magnetization reversal in a GaMnAs film grown on a Si substrate was investigated using planar Hall effect measurements. The angular dependence of the planar Hall resistance (PHR) shows that cubic crystalline anisotropy along the h100i directions dominates the film's magnetic anisotropy. However, the magnetization reversal behavior varies significantly with the applied field strength: as the magnetic field strength decreases, the PHR amplitude decreases, and hysteresis appears in data obtained with clockwise and counterclockwise rotation of the field directions. Furthermore, asymmetry in the PHR amplitude between the two opposite field directions appears during the angle scan and increases with decreasing field strength. We show that these features arise from a broad distribution of magnetic domains having different pinning fields.