Spin-dependent transport properties of three-terminal ferromagnetic-semiconductor heterostructures with a GaMnAs quantum well and double barriers: Control of quantum levels and TMR

We investigate the spin-dependent tunneling properties of three-terminal GaMnAs quantum-well (QW) double-barrier devices containing a QW electrode to control the spin-dependent quantum levels of the GaMnAs QW. We successfully modulate the quantum levels of the GaMnAs QW and control the spin-dependent current by changing the voltage of the QW electrode ($V_{QW}$). Also, tunneling magnetoresistance increase is observed at resonant levels by changing $V_{QW}$. This work was partly supported by Grant-in-Aids for Scientific Research, the Special Coordination Programs for Promoting Science and Technology, R\&D for Next-generation Information Technology by MEXT, and PRESTO of JST.