Numerical investigation of quantum tunneling time and spin-current density in GaAs/GaMnAs/GaAs barriers: Role of an applied bias voltage

In this paper, we have discussed theoretically the effect of an applied bias voltage and the temperature on the spin-tunneling time, spin-dependent polarization and current densities of holes in GaAs/GaMnAs double barriers using the transfer matrix method (TMM). The behavior of the transmission coefficients for different spin orientations (up and down), various applied voltages and different temperatures were calculated. Our findings indicate that the maxima of the spin-up transmission coefficient shift towards the lower energies by increasing the applied bias voltage. Furthermore, our structure is almost transparent for spin-down holes and presents some resonances for spin-up ones. In addition, we have found that the tunneling time decreases progressively by enhancing the applied voltage. It is also shown that the current densities of holes with both spin-up and down orientations present a negative differential resistance (NDR). This (NDR) resistance is more intense for spin-up holes than spin-down ones. Consequently, the obtained results pointed out that we can design and fabricate a high-speed spin-filters and diodes by fixing the appropriate values of applied voltages and temperatures.