Interface resistance and transparency in ferromagnet/superconductor Co Nbx Ti1-x multilayers (x=1, 0.6, and 0.4)

The quantitative interface resistance between polycrystalline ferromagnetic Co and Nbx Ti1-x, with x=1, 0.6, and 0.4, is measured and analyzed at 4.2 K. Both the superconducting and normal states of Nbx Ti1-x, respectively, above and below the superconducting critical thickness, are studied with current flowing perpendicular to the interface. A one-band series-resistance model is used to analyze our data. The interface transparencies in terms of the ratio between interface resistance and various physical quantities are discussed.