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 Hanle-effect 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.