Large tunneling magnetoresistance (>70%) in GaMnAs/AlAs/GaMnAs single-barrier ferromagnetic semiconductor tunnel junctions

We have observed very large tunneling magneto-resistance (TMR) in GaMnAs/AlAs/GaMnAs single-barrier ferromagnetic semiconductor tunnel junctions grown on a (0 0 1) GaAs substrate by low-temperature molecular beam epitaxy. The TMR ratio of 72 % was obtained in a junction with a thin (1.6 nm) AlAs tunnel barrier when the magnetic field was applied along the [1 0 0] axis in the film plane. The TMR ratio was larger when the applied magnetic field direction was along [1 0 0], compared with other directions of [1 1 0] and [−1 1 0]. Also, the TMR ratio was found to decrease with increasing the AlAs barrier thickness.