  We have measured the transport properties of Ferromagnet - Superconductor
nanostructures, where two superconducting aluminum (Al) electrodes are
connected through two ferromagnetic iron (Fe) ellipsoids in parallel. We find
that, below the superconducting critical temperature of Al, the resistance
depends on the relative alignment of the ferromagnets' magnetization. This
spin-valve effect is analyzed in terms of spin accumulation in the
superconducting electrode submitted to inverse proximity effect.
