  We present a detailed analysis of the relativistic electronic structure and
the momentum dependent spin-polarization of the Tl/Si(111) surface. Our first
principle calculations reveal the existence of fully spin-polarized electron
pockets associated to the huge spin-splitting of metallic surface bands. The
calculated spin-polarization shows a very complex structure in the reciprocal
space, strongly departing from simple theoretical model approximations.
Interestingly, the electronic spin-state close to the Fermi surface is
polarized along the surface perpendicular direction and reverses its
orientation between different electron pockets.
