Achievement of a spin polarization without magnetic field through a GaMnN based ferromagnetic resonant tunneling diode (RTD) is proposed theoretically. The influences of the temperature and structure on the spin polarization current and differential conductance have been investigated. The clear spin splitting current can be observed in an optimal RTD structure without magnetic field even though the splitting energy of the ferromagnetic barrier is very small. Large spin polarization can be obtained and the polarization orientation can be varied by an applied bias voltage without external magnetic field.

We propose a spin selector of ferroelectric triple barrier resonant tunneling diode with diluted magnetic quantum wells. Spin transport properties of this spin selector are investigated by nonequilibrium Green’s function method. Results show the oscillation of spin polarization of current occurred at low bias voltage due to a transmission resonant peak splitting into subpeaks. By reversing the electric dipole direction of ferroelectric barriers, the spin direction of polarized current is reversed simultaneously at a fixed bias voltage. This implies that the spin direction of injected current can be selected through this spin selector without changing the applied magnetic field.