Preparation and Properties of Thin-Film Hard Superconductors

Films of thickness the order of 1000 Å of Nb-Zr, Nb-Ti, Ti-V, V-Si, Nb-Sn, and Nb have been prepared by dc sputtering and by electron bombardment evaporation. Measurement of the critical current Jc as a function of external magnetic field H was carried out at 4.2°K by using pulsed magnetic fields and pulsed currents. The films have Jc vs H characteristics and transition temperatures very similar to those reported for bulk hard superconductors. An exception was the sputter-deposited Nb, Tc≈9°K, which was superconducting at 70 kOe and 103 A/cm2. More structure was observed in the Jc vs H characteristic for longitudinal configuration than previously reported.