  We investigate the spin-dependent tunneling properties in a three-terminal
III-V-based ferromagnetic-semiconductor heterostructure with a 2.5-nm-thick
GaMnAs quantum well (QW) and double barriers. We successfully control the
quantum levels and modulate the spin-dependent current with varying the voltage
of the electrode connected to the GaMnAs QW. Our results will open up a new
possibility for realizing three-terminal spin resonant-tunneling devices.
