Interplay between spin-relaxation and Andreev reflection in ferromagnetic wires with superconducting contacts

We analyze the change in the resistance of a junction between a diffusive ferromagnetic (F) wire and normal-metal electrode, due to the onset of superconductivity (S) in the latter and a double Andreev scattering process leading to a complete internal reflection of a large fraction of the spin-polarized electrons back into the ferromagnet. The superconducting transition results in an additional contact resistance arising from the necessity to match the spin-polarized current in F wire to the spinless current in S reservoir, which is comparable to the resistance of a piece of a F wire with the length equal to the spin-relaxation length. [S0163-1829(99)03342-1].