Suppression of the superconductivity by the spin-polarized current injection through mesoscopic ferromagnet/superconductor junctions

We observed suppression of the superconductivity in a mesoscopic superconducting Al wire in proximity contact with an overlaid ferromagnetic Co wire. The suppression, as evidenced by the reduction of the critical current, was most pronounced when the spin-polarized current was injected through the Co/Al interface. The spin-diffusion length, estimated from the finite resistance over a certain length of Al wire near the interface, increased with temperature approaching T-c from below. This looks to suggest that the spin-diffusion length in the superconducting state may be correlated with the superconducting coherence length.