Local Hanle-effect studies of spin drift and diffusion in n:GaAs epilayers and spin-transport devices

In electron-doped GaAs, we use scanning Kerr-rotation microscopy to locally probe and spatially resolve the depolarization of electron spin distributions by transverse magnetic fields. The shape of these local Hanleeffect curves provides a measure of the spin lifetime as well as spin transport parameters including drift velocity, mobility and diffusion length. Asymmetries in the local Hanle data can be used to reveal and map out the effective magnetic fields due to spin–orbit coupling. Finally, using both spin imaging and local Hanle effect studies, we investigate the drift and diffusion of electrically-injected spins in lateral Fe/GaAs spin-detection devices, both within and outside the current path. 5 Present address: Department of Physics, University of Vermont, Burlington, VT 05405, USA. 6 Present address: Cavendish Laboratory, JJ Thomson Ave, Cambridge CB3 0HE, UK. 7 Author to whom any correspondence should be addressed. New Journal of Physics 9 (2007) 347 PII: S1367-2630(07)50586-