Orientation dependence of grain-boundary critical currents in c-axis Y1Ba2Cu3O7 thin films and step-edge Josephson junctions

The critical current densities across grain boundaries have been measured as a fonction of the in-plane crystallographic orientations of c-axis Y1Ba2Cu3O7 thin films grown on different lattice-mismatched substrates by inverted-cylindrical-magnetron sputtering technique. The in-plane orientation of the grain boundaries can be controlled by the lattice-mismatch of substrates, the substrate temperature and oxygen pressure used during the deposition. We found that 45 degrees- angle grain boundaries don't show weak-link behavior characteristic of Josephson junctions.