A theory of the proximity effects of the exchange splitting in a ferromagnetic metal on a two-dimensional electron gas (2DEG) in a semiconductor is presented. The resulting spin-dependent energy and lifetime in the 2DEG create a marked spin splitting in the driven in-plane current. The theory of the planar transport allows for current leakage into the ferromagnetic layer through the interface, which leads to a competition between drift and diffusion. The spin-dependent in-plane conductivity of the 2DEG may be exploited to provide the possibility for spintronics devices based on planar devices in a field-effect transistor configuration. An illustrative example is provided through the transport theory of a proposed spin valve which consists of a field-effect transistor configuration with two ferromagnetic gates. Results are provided for two experimentally accessible systems: the silicon inversion layer and the naturally formed InAs accumulation layer.

• Received 15 September 2003

DOI:https://doi.org/10.1103/PhysRevB.69.115339