Improved grain boundary currents in textured YBa_2Cu_3O_(delta) thin films on bicrystalline Ni substrates

摘要

Using magneto optical imaging a comparative study of YBa_2Cu_3O_(delta) thin films grown on Gd- 10 at percent doped CeO_2 buffered Ni and SrTiO_3 bicrystals with tilt angles ranging from 3 deg to 16 deg has been made. The Ni substrates have been chosen as a model system for the RABiTS coated conductor technology. It is found that the YBa_2Cu_3O_(delta) 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.