Pinning behavior of Nb3Ge thin film superconductors

Nb3Ge thin film superconductors have been prepared by coevaporation and cosputtering on hot sapphire substrates. Films were analyzed by X-ray and backscattering techniques. Critical current density, jc, has been determined between 4.2 K and Tcin magnetic fields up to 13 Tesla, upper critical field, Bc2was obtained from resistive transition or by extrapolation from jc. Pinning in coevaporated films obeys temperature scaling, whereas cosputtered films have their pinning maximum at a constant field value, Bp. A correlation between Bpand the Nb3Ge film microstructure is suggested as pinning increases with Bp.