Four states memory function in GaMnAs ferromagenic semiconductor epilayer

GaMnAs ferromagnetic semiconductor has strong biaxial in-plane anisotropy, which generates four stable magnetization easy axes at zero magnetic field. This feature results in double switching behavior in the main loop of planar Hall resistance (PHR) spectrum. The minor loops of PHV spectrum exhibited four stable states corresponding to four magnetic easy axes at zero magnetic field. This feature clearly demonstrates the possibility of quaternary memory device application using GaMnAs ferromagnetic semiconductor.