Improved grain boundary currents in textured YBa2Cu3O delta thin films on bicrystalline Ni substrates

Using magneto optical imaging a comparative study of YBa2Cu3Odelta thin films grown on Gd-10at% doped CeO2 buffered Ni and SrTiO3 bicrystals with tilt angles ranging from 3degrees to 16degrees has been made. The Ni substrates have been chosen as a model system for the RABiTS coated conductor technology. It is found that the YBa2Cu3Odelta grain boundaries on Ni exhibit improved superconducting transport properties, while for the intra-granular critical currents a moderate decrease is observed. The improved J(gb)/J(c) ratio could be detected for all studied grain boundary angles as well as over the whole accessible temperature range from 8 to 60 K. Extensive x-ray measurements on the in- and out-of-plane texture of all layers have been performed to explain the change in the intra- and inter-granular critical currents.