Bulk and surface spin-orbit relaxation of the conduction electrons separated by weak-localization experiments

Weak-localization magnetoresistance measurements allow a determination of the spin-orbit relaxation time in thin metal films. We have performed a series of experiments on films of magnesium metal evaporated on several different substrates with a range of film thicknesses, and for the first time separated the spin-orbit relaxation rate in the bulk of magnesium from that at the surface. Whereas the spin disorientation per bulk (elastic) scattering is intrinsic to the element (magnesium) under consideration, the surfaces on which the metal film is evaporated can give rise to a spin-orbit interaction that differs by more than an order of magnitude for different substrates.