Spin-polarized transport in II-VI magnetic resonant tunneling devices

We investigate electronic transport through II-VI semiconductor resonant tunneling structures containing diluted magnetic impurities. Due to the exchange interaction between the conduction electrons and the impurities, there arises a giant Zeeman splitting in the presence of a moderately low magnetic field. As a consequence, when the quantum well is magnetically doped the current-voltage characteristics shows two peaks corresponding to transport for each spin channel. This behavior is experimentally observed and can be reproduced with a simple tunneling model. The model thus allows to analyze other configurations. First, we further increase the magnetic field, which leads to a spin polarization of the electronic current injected from the leads, thus giving rise to a relative change in the current amplitude. We demonstrate that the spin polarization in the emitter can be determined from such a change. Furthermore, in the case of a magnetically doped injector our model shows a large increase in peak amplitude and a shift of the resonance to higher voltages as the external field increases. We find that this effect arises from a combination of giant Zeeman splitting, 3-D incident distribution and broad resonance linewidth.