Spin injection in ferromagnet–superconductor/normal–ferromagnet structures

We have fabricated multi-terminal devices consisting of three parallel ferromagnetic (FM) electrodes with tunnel junction contacts to a 100nm wide Al strip. A spin polarized current injected from one FM electrode into the Al strip can be detected at the other FM electrodes. The spin diffusion length and polarization in Al are measured at room temperature (RT), and at 4K. No magnetoresistance (MR) over two junctions in series could be measured with the strip in the normal state. A weak MR is observed in the superconducting (S) state.