  We report an observation of spin-valve like hysteresis within a few atomic
layers at a ferromagnetic interface. We use phonon spectroscopy of nanometer
sized point contacts as an in-situ probe to study the mechanism of the effect.
Distinct in energy phonon peaks for contacts with dissimilar nonmagnetic outer
electrodes allow to localize the observed spin switching to the top or bottom
interfaces for nanometer thin ferromagnetic layers. The mechanism consistent
with our data is energetically distinct atomically thin surface spin layers
that can form current or field driven surface spin-valves within a single
ferromagnetic film.
