High spin filtering using multiple magnetoelectric barriers

A periodic array of magnetoelectric barriers is modeled to achieve maximum spin polarization (P) at high transmission probability (T). Each double-pair unit of the array consists of four magnetic barriers designed in several ways, such that an electron passing through, in the Landau gauge A=(0,A(y)(x),0), acquires zero gain in kinetic energy. This enables multiple double-pairs to be used to enhance P without sacrificing T. By tuning the magnetoelectric barrier heights, a high P of 75%-100% is obtained at 0.8-1.0E(F), for a 27 unit array. For antisymmetrical arrays, electrical barriers act as a switch to the polarization capability. (C) 2004 American Institute of Physics.