EFFECTS OF WEAK INTERGRAIN COUPLING IN THE TRANSPORT-PROPERTIES OF TEXTURED YBCO THIN-FILMS

We present a study of the influence of the intergrain coupling on the transport properties of YBa2Cu3O7-x films. Two sets of samples have been analyzed: highly textured c oriented thin films (approximately 1000 angstrom) and thick samples (approximately 1 mum) with a polycrystalline structure and mixed (001) and (103) orientations. Textured samples showed critical currents of 3 x 10(5) A cm-2 while the thicker polycrystalline ones had 10(3) A cm-2 at 77 K. Resistance and critical currents have been measured under magnetic fields (0, 0.3, 0.6, 0.9, 1.2, 1.5 and 1.8 T) applied parallel and perpendicular to the c-axis to get information on the influence of the multiple orientations on the intergrain coupling. A weak intergrain coupling is found to be responsible for the low critical currents in the thicker samples.