Coupling effects of layers on spin transport in ZnSe/Zn1-xMnxSe heterostructures

By use of the scattering matrix method, we investigate the coupling effects of layers on spin-polarized transport through semimagnetic semiconductor heterostructures with triple paramagnetic layers. Due to the coupling between double non-magnetic layers or among triple paramagnetic layers, spin tunneling exhibits interesting and complex features, which are determined by the structural configuration, the external fields as well as the spin orientations. It is shown that for electrons with either spin orientation tunneling through the symmetric or asymmetric heterostructures with triple paramagnetic layers, transmission resonances can approach the optimum under several biases. Moreover, for asymmetric structures, the resonant enhancement can occur under both several positive and negative biases. The spin-dependent resonant enhancement is also clearly reflected in the current density. In addition, for spin electrons traversing the multilayer heterostructure, the resonant splitting occurs in the transmission, which shows rich variations with the bias. These interesting results may be helpful to the development of spintronic devices.