Electric Field Induced Suppression of the Magnetoresistance of Dilute Magnetic Semiconductor Trilayers

In semiconductor spintronic devices, the semiconductor is usually lightly doped and nonde-generate, and moderate electric fields can dominate the carrier motion. We recently derived a drift-diffusion equation for spin polarization in the semiconductors by consistently taking into account electric-field effects and nondegenerate electron statistics and identified a high-field diffusive regime that has no analog in metals. Here high fields are argued to substantially reduce the magnetoresistance observable in a recent experiment on magnetic-semiconductor– nonmagnetic-semiconductor–magnetic-semiconductor trilayers. KEY WORDS: magnetoresistance; semiconductor spintronics; spin transport. 1