CRITICAL CURRENT MEASUREMENTS IN YBA2CU3O7-X THIN-FILM GROWN ON LAALO3 SUBSTRATE

The critical current density Jc(B,T) of epitaxial YBa 2Cu3O7-x (YBCO) thin films on LaAlO3 was measured under different applied magnetic fields (0-7 T) with the temperature ranging from 65 to 79 K. At 65 K, the zero-field critical current density of the best film was 5.8×106 A/cm2; even at magnetic fields up to 7 T, Jc could reach as high as 1×10 6 A/cm2. Strong anisotropy was observed at 79 K. The anisotropy behavior diminished with the decrease of temperature. Experimental results showed that Jc was proportional to (Tc-T) 3/2; this was in accordance with the theoretical explanation by the Josephson junction model for granular superconductors.