Spin filtering in a two-dimensional electron gas device with asymmetric spatially spread magnetic-electric barriers

Abstract

We calculate, based on the effective mass Hamiltonian, the spin dependence of ballistic transport through a two-dimensional electron gas (2DEG) under the influence of an electric U and a pair of magnetic B barriers with finite spatial width. The spin polarization of electron transmission P is strongly dependent on the degree of asymmetry in the magnetic barriers. An asymmetry in the B barrier widths and heights which conserves the magnetic vector potential A along the conduction path leads to a low P of less than 1% in the high transmission region. If conservation of A is broken, much higher P values of up to 30% is achievable but at the cost of increasing the energy threshold Eth. Finally, we suggest a scheme which utilizes a thin break in the 2DEG conduction path to achieve a comparable modulation of P of 25%, while conserving A and maintaining Eth at moderate electron energies.