Quantum transport of spin-polarized carriers in quasi paramagnetic quantum wires: Green's function formalism

The spin-dependent electrical conductance and magnetoresistance (MR) of a one-dimensional system are calculated with disorder paramagnetic impurities. The system contains a quasi-paramagnetic quantum wire (QPQW) device attached between two non-magnetic semi-infinite leads. The calculations are based on the tight-binding model and generalized Green's function method within the phase coherent transport regime. In order to investigate spin-filtering effect of QPQW, we study the spin-polarized electrical transmission as a function of impurity concentration and molecular field acting on paramagnetic impurities. It is assumed that in the absence of the external field, magnetic moments of the impurities are compensated (oriented at random), whereas the magnetic field creates finite net magnetization. It is found that the spin-dependent transport and MR depend strongly on the concentration of magnetic disorder, the size of the system and the Fermi energy. It is shown that MR has an oscillating behavior with respect to the magnetic molecular field at a fixed disorder concentration. The application of the predicted results can be a base for the designing of spintronics and moletronics devices.