Size- and voltage-dependent spin polarization in hybrid ferromagnetic-Schottky-metal and semiconductor nanostructure

Recently, an electron-spin filter was proposed by depositing two nanosized ferromagnetic metal stripe and Schottky normal metal stripe on the top of the semiconductor heterostructure [F. Zhai, H.Q. Xu, Y.Guo, Phys. Rev. B 70 (2004) 085308]. In this paper, we theoretically investigate the effect of device parameters on electron-spin polarization in the spin filter. It is shown that the electron-spin polarization is dependent greatly on the sizes and the position of the stripes. Thus, a quantum size effect exists in this device and the optimal spin polarization can be achieved by felicitously fabricating the stripes. It also is shown that the spin polarization can be altered by adjusting the electric-barrier height induced by an applied voltage to the Schottky metal stripe, which can result in a voltage-tunable electron-spin filter.