Spin-polarized transport and Andreev reflection in semiconductor/superconductor hybrid structures

We show that spin-polarized electron transmission across semiconductor/supe rconductor (Sm/S) hybrid structures depends sensitively on the degree of sp in polarization as well as the strengths of potential and spin-flip scatter ing at the interface. We demonstrate that increasing the Fermi velocity mis match in the Sm and S regions can lead to enhanced junction transparency in the presence of spin polarization. We find that the Andreev reflection amp litude at the superconducting gap energy is a robust measure of the spin po larization magnitude, being independent of the strengths of potential and s pin-flip scattering and the Fermi velocity of the superconductor. [S0163-18 29(99)50248-8].