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 parallel with direct tunneling. The spin accumulation Δμᶜʰ 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 Δμᶜʰ and the spin accumulation Δμˡˢ in the localized states. In the regime where Δμˡˢ/Δμᶜʰ is largest, the detected spin signal is insensitive to Δμˡˢ and the ferromagnet probes the spin accumulation in the semiconductor channel.