Spin injection in ferromagnet-semiconductor heterostructures at room temperature (invited)

In this article we summarize our recent work on room-temperature spin injection in Fe/GaAs and MnAs/GaAs heterostructures. The most critical issue for injection of spin polarized electrons (holes) from the ferromagnet (FM) into the semiconductor (SC) is the control of the atomic arrangement at the FM/SC interface during molecular beam epitaxial growth of these rather dissimilar materials. For many years the formation of a magnetically dead layer at the Fe/GaAs interface has prevented spin injection. In addition to the accurate control of the FM/SC interface, the formation of a Schottky barrier between FM and SC for efficient spin injection via tunneling is the second critical issue for successful experiments. We describe in detail our approaches to solve these problems.