  We present a study of the influence of an external magnetic field H and an
electric current I on the spin-valve (SV) effect between a ferromagnetic thin
film (F) and a sharp tip of a nonmagnetic metal (N). To explain our
observations, we propose a model of a local surface SV which is formed in such
a N/F contact. In this model, a ferromagnetic cluster at the N/F interface
plays the role of the free layer in this SV. This cluster exhibits a larger
coercive field than the bulk of the ferromagnetic film, presumably due to its
nanoscale nature. Finally, we construct a magnetic state diagram of the surface
SV as a function of I and H.
