Spin-dependent tunneling transport in a ferromagnetic GaMnAs and un-doped GaAs double-quantum-well heterostructure

We investigate the spin-dependent tunneling transport in a ferromagnetic GaMnAs and un-doped GaAs double-quantum-well heterostructure. Clear tunneling magnetoresistance (TMR) and negative differential resistance due to the strong resonant tunneling in the GaAs quantum well (QW) are demonstrated in this device. We show that TMR oscillates as a function of the bias voltage following the dI/dV-V characteristics, and TMR becomes negative at biases where resonant tunneling occurs. These results can be explained by the difference of the potential drops in the magnetic tunnel junction composed of the top GaMnAs/AlAs/GaMnAs-QW between parallel and anti-parallel magnetization. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4704154]