Injection and detection of spin in a semiconductor by tunneling via interface states

Injection and detection of spin accumulation in a semiconductor having localized states at the interface is evaluated. Spin transport from a ferromagnetic contact by sequential, two-step tunneling via interface states is treated not in itself, but in parallelwith direct tunneling. The spin accumulation dμch induced in the semiconductor channel is not suppressed, as previously argued, but genuinely enhanced by the additional spin current via interface states. Spin detection with a ferromagnetic contact yields a weighted average of dμch and the spin accumulation dμls in the localized states. In the regime where dμls/dμch is largest, the detected spin signal is insensitive to dμls and the ferromagnet probes the spin accumulation in the semiconductor channel.