Symmetrical high-T-c superconducting bicrystal Josephson junctions: Dependence of the electrical properties on the misorientation angle

The electrical properties of junctions at symmetrical bicrystal boundaries in high-T-c superconducting films are studied as functions of the misorient ation angle in the range 8 degrees -45 degrees. The junctions are prepared by growing YBa2Cu3O7 (YBCO) epitaxial films on Y-ZrO2 (YSZ) bicrystal subst rates. The proportional relationship between the characteristic voltages an d the normal conductivities of junctions is derived from the dependences of the critical current and the normal resistance on the misorientation angle . The results are interpreted within the model of a superconductor-dielectr ic with defect levels in the hand gap of the superconductor. The deviations from the proportional relationship are explained by the junction inhomogen eity. The thickness of the effective dielectric layer in the bicrystal junc tion and the Bohr radius of electrons on the defects are estimated. (C) 200 1 MAIK "Nauka/Interperiodica".