Spin filtering in magnetic barrier structures with in-plane spin orientation

We investigate ballistic spin transport in a two-dimensional electron-gas system containing magnetic barriers of various geometries by using the transfer matrix method. While most previous studies have focused on the effect of magnetic barriers perpendicular to the two-dimensional electron gas plane, we concentrate on the case of magnetic barriers parallel to the plane. We show that resonant oscillation occurs in the lower incident energy region in the transmission probability without any electrostatic potential compensation, which is an essential ingredient in the case of magnetic barriers perpendicular to the plane. The transmission probability in the magnetic barrier structure changes drastically according to the number of barriers and according to the additional electrostatic potential modulation applied in the magnetic barrier region. Using a hybrid model consisting of a superconductor, ferromagnets, and a two-dimensional electron gas plane, we show that the hybrid quantum structure can serve as a good spin filter, which can be operated totally by electrical modulation without any magnetic control.