  Point contacts between normal and ferromagnetic metals are investigated using
magneto-resistance and transport spectroscopy measurements combined with
micromagnetic simulations. Pronounced hysteresis in the point-contact
resistance versus both bias current and external magnetic field are observed.
It is found that such hysteretic resistance can exhibit, in addition to
bi-stable resistance states found in ordinary spin valves, tri-stable
resistance states with a middle resistance level. We interpret these
observation in terms of surface spin-valve and spin-vortex states, originating
from a substantially modified spin structure at the ferromagnetic interface in
contact core. We argue that these surface spin states, subject to a weakened
exchange interaction, dominate the effects of spin transfer torques on the
nanometer scale.
