TWIN-FREE YBA2CU3O7-DELTA FILMS ON (001)NDGAO3 SHOWING ISOTROPIC ELECTRICAL BEHAVIOR

Investigating the epitaxial nature of YBa2Cu3O7-delta films on NdGaO3 (001) by Rutherford backscattering (RES) and X-ray diffraction (XRD) t exture measurements we find that the films are almost single crystalli ne, in the sense that the a, b and c axes are uniquely defined with re spect to those of NdGaO3. The crystalline perfection is, however, not reflected in the electrical properties of the films. Although we measu re a T-c of 89.7 K, we did not observe the expected anisotropy in the resistivity. We interpret this to be due to Ga diffusion from the subs trate into the film which effectively blocks the chain conductivity.