We study spin transport in a superconducting nanowire using a set of closely spaced magnetic tunnel contacts. We observe a giant enhancement of the spin accumulation of up to 5 orders of magnitude on transition into the superconducting state, consistent with the expected changes in the density of states. The spin relaxation length decreases by an order of magnitude from its value in the normal state. These measurements, combined with our theoretical model, allow us to distinguish the individual spin-flip mechanisms present in the transport channel. Our conclusion is that magnetic impurities rather than spin-orbit coupling dominate spin-flip scattering in the superconducting state.

We have grown epitaxial spinel ferrite thin films of (Mn,Zn) Fe2O4 and CoFe2O4 on (100) and (110) SrTiO3 and MgAl2O4 buffered by spinel structure buffer layers. High quality spinel ferrite films were grown at 400 °C on buffer layers that were grown at 600 °C and postannealed at 1000 °C. Although (Mn,Zn) Fe2O4 grown directly on SrTiO3 and MgAl2O4 shows mediocre structural and magnetic properties, ferrite films grown on (100) and (110) SrTiO3 and MgAl2O4 buffered with CoCr2O4 exhibit excellent crystallinity and bulk saturation magnetization values, thus indicating the importance of lattice match and structural similarity between the film and the immediately underlying layer.

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