Observation of Spin Injection at a Ferromagnet-Semiconductor Interface

Spin injection at a ferromagnet-semiconductor interface is observed by projecting the spin-polarized current in the ferromagnet onto the spin-split density of states of a high mobility two-dimensional electron gas (2DEG). For a given polarization of carriers in the 2DEG, reversing the magnetization orientation of the ferromagnet modulates the interface resistance. Equivalently, reversing the polarization of the 2DEG carriers by reversing the bias polarity gives the same resistance modulation. Interface resistance changes of order 1% at room temperature indicate interfacial current polarizations of order 20%.