  In contrast to the long-known fact that spin-flip hot spots, i.e., special
\vc{k}-points on the Fermi surface showing a high spin-mixing parameter, do not
occur in the bulk of monovalent (noble and alkali) metals, we found them on the
surface Brillouin-zone boundary of ultrathin films of these metals.
Density-functional calculations within the Korringa-Kohn-Rostoker Green
function method for ultrathin (001) oriented Cu, Ag, and Au films of 10-layer
thickness show that the region around the hot spots can have a substantial
contribution, e.g.\ 52\% in Au(001), to the integrated spin-mixing parameter,
that could lead to a significant enhancement of the spin-relaxation rate or
spin-Hall angle in thin films. Owing to the appearance of spin-flip hot-spots,
a large anisotropy of the Elliott-Yafet parameter [50\% for Au(001)] is also
found in these systems. The findings are important for spintronics applications
in which noble-metals are frequently used and in which the dimensionality of
the sample is reduced.
