  The spin-selective electron reflection at a ferromagnetic-paramagnetic
interface is investigated using Fe films on a W(110) substrate. Angle-resolved
photoemission of the majority and minority Fermi surfaces of the Fe film is
used to probe standing wave formation. Intense quantum well states resulting
from interfacial reflection are observed exclusively for majority states. Such
high spin polarization is explained by the Fermi surface topology of the
connecting substrate, and we argue that Fe/W is a particularly suitable
interface for that purpose.
