COMPARISON OF THE CRITICAL-CURRENT ANISOTROPY IN EPITAXIAL YBA2CU3O7-X FILMS ON (100) LAAL2O3 AND (100) YTTRIA-STABILIZED ZIRCONIA

The angular magnetic field dependence of the critical current density J(c)(theta) of epitaxial YBa2Cu3O7 thin films is presented in the temperature regime close to T-c. The high temperature behavior of J(c)(theta) shows features that are significantly different from the earlier observations at lower temperatures. A comparison between the films on (100) LaAlO3 and (100) yttria stabilized zirconia (YSZ) indicates significant differences that may be attributed to the differences in the microstructure of the films on the two substrates. In particular, the observation of enhanced pinning in the films on YSZ may be due to the pinning effects of the low angle grain boundaries present in these films.