  We present electrical transport experiments performed on submicron hybrid
devices made of a ferromagnetic conductor (Co) and a superconducting (Al)
electrode. The sample was patterned in order to separate the contributions of
the Co conductor and of the Co-Al interface. We observed a strong influence of
the Al electrode superconductivity on the resistance of the Co conductor. This
effect is large only when the interface is highly transparent. We characterized
the dependence of the observed resistance decrease on temperature, bias current
and magnetic field. As the differential resistance of the ferromagnet exhibits
a non-trivial asymmetry, we claim that the magnetic domain structure plays an
important role in the electron transport properties of superconducting /
ferromagnetic conductors.
