  Using first-principles methods based on density-functional theory we
investigate the spin relaxation in W(001) ultrathin films. Within the framework
of the Elliott-Yafet theory we calculate the spin mixing of the Bloch states
and we explicitly consider spin-flip scattering off self-adatoms. We find an
oscillatory behavior of the spin-mixing parameter and relaxation rate as a
function of the film thickness, which we trace back tosurface-state properties.
We also analyze the Rashba effect experienced by the surface states and discuss
its influence on the spin relaxation. Finally we calculate the anisotropy of
the spin-relaxation rate with respect to the polarization direction of the
excited spin population relative to the crystallographic axes of thefilm. We
find that the spin-relaxation rate can increase by as much as 47% when the spin
polarization is directed out of plane, compared to the case when it is in
plane. Our calculations are based on the multiple-scattering formalism of the
Korringa-Kohn-Rostoker Green-function method.

Materials Science