Imaging spin flows in semiconductors subject to electric, magnetic, and strain fields

Using scanning Kerr microscopy, we directly acquire two-dimensional images of spin-polarized electrons flowing laterally in bulk epilayers of nGaAs. Optical injection provides a local dc source of polarized electrons, whose subsequent drift and/or diffusion is controlled with electric, magnetic, and-in particular-strain fields. Spin precession induced by controlled uniaxial stress along the < 110 > axes demonstrates the direct k-linear spin-orbit coupling of electron spin to the shear (off diagonal) components of the strain tensor, epsilon(xy).