Fabrication of all thin-film YBa2Cu3O7−δ /Pb Josephson tunnel junctions

Abstract

All thin-film YBCO/Pb Josephson tunnel junctions have been fabricated. The junctions showed a well-defined Pb gap, Pb phonon structures, and very low leakage current. In addition, a higher bias spectroscopy revealed identical structures as have been seen in junctions made with single-crystal YBCO. A thin uniform Ag diffusion barrier at the junction interface lowers the junction resistance enough to study the Josephson effct in YBCO/Pb tunnel junctions. Both the temperature and the magnetic field dependencies of the magnitude of the Josephson current displayed conventional behavior. The junctions were very reproducible and uniform as indicated by the Ic(B) pattern.