Spin transport and spin current detection in semiconductors

We consider a semiconductor device similar to the subject of recent experiments on the spin-dependent Hall effect and analyse electric field effects in spin transport. A drift-diffusion equation for spin density is derived, and drift and diffusion contributions to the spin current are examined, which importantly suggests a possible way for the enhancement of spin current by using a semiconductor degenerate regime. By referring to the experimental detection technique, an expression for the transverse Hall field arising from the spin current is derived, whose exponential dependence on distance at electric fields near E similar or equal to E-co can also be used as a convenient and useful tool to determine the spin diffusion length of a semiconductor. The results are discussed and are compared with published experimental data. (C) 2007 Elsevier Masson SAS. All rights reserved.