Anisotropic tunneling magnetoresistance in GaMnAs/AlAs/GaMnAs ferromagnetic semiconductor tunnel junctions

We have observed very large tunneling magnetoresistance (TMR) in Ga1-xMnxAs/AlAs/Ga1-xMnxAs ferromagnetic semiconductor tunnel junctions. A TMR ratio as high as 75% was obtained in a junction with a thin (1.5 nm) AlAs tunnel barrier when the magnetic field was applied along the [100] axis in the film plane. The TMR ratio decreased when the applied magnetic field direction was along the [1(1) over bar $0] and [110]. This anisotropic TMR was found to be explained by the single-domain theory assuming cubic magnetic anisotropy with the easy axis of [100], which is induced by the zincblende-type Ga1-xMnxAs crystal structure. (C) 2001 American Institute of Physics.