Electric Field Effects on Spin Polarized Transport in FM/NMS and FM/NMS/FM Structures in Interaction Approximation

In this article, we have solved spin-dependent drift-diffusion equations analytically by considering a spin selective barrier between the magnet and semiconductor layer in interaction approximation and also taking into account the correlation and exchange effects. We have studied the electric field effects on the spin polarized transport in the ferromagnetic/nonmagnetic semiconductor (FM/NMS) and FM/NMS/FM structures in a degenerate regime. We have shown by increasing the conductivity of semiconductor up to ferromagnetic conductivity, semiconductor effective resistance becomes smaller and the spin injection efficiency will be increased. Also, the electric field enhances spin polarization density. Furthermore, in injection structures with interfacial barriers, the electric field enhances spin polarization considerably. In fact, the spin selective interfacial barrier acts as a spin filter, which permits electrons with a particular spin direction ↑(↓) pass through the interface. In addition, the calculated results in interacting approximation show that spin injection is increased. Finally, it is found that in FM/NMS/FM structures at low-field regime, the width of the semiconductor has the important role in spin transport.