Tunneling measurements on spin-paired superconductors with spin-orbit scattering

Electron spin effects in superconducting Al films have been studied by measuring the conductance of tunnel junctions in a magnetic field. Superconductor-normal-metal tunnel junctions were made with 50-{}-thick Al and 500-1000-{}-thick Ag films with Al₂{O}₃$ as the barrier. The measured conductance curves were fit by theoretical calculations, which included depairing effects and spin-orbit scattering, and values of the depairing parameter ${{ζ}}₀$ and the spin-orbit parameter ${b}₀$ were obtained. The relation ${{ζ}}₀={ζ}(0)+{C {H}²}{{{Δ}}₀}$ was found to describe the (parallel) magnetic field dependence of the depairing. The values of ${b}₀$ obtained were independent of $H. Superconductor-superconductor tunnel junctions made with two 50--thick Al films were studied with various amounts of Ge and Mn impurities. The Ge impurity simply raised{T}c$, whereas the Mn lowered ${T}c$ and increased ${b}₀$. The approximate dependence of ${b}₀$ on the Mn impurity concentration was obtained. The qualitative features for spin-orbit scattering predicted by theory were observed, and spin-flip scattering in the tunneling process was shown to be negligible.