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.