The variation of J/sub cgb/ with GB misorientation and inclination measured using the scanning SQUID microscope

The scanning SQUID microscope was used to measure the Josephson penetration length (/spl lambda//sub J/) along the grain boundary. The J/sub c/ across the grain boundary was then derived from the /spl lambda//sub J/. YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) films were deposited on a special set of SrTiO/sub 3/ bicrystals to determine whether J/sub cgb/ varies as function of boundary inclinations (/spl alpha/'s). Our results showed that J/sub cgb/ decreased with /spl alpha/ while /spl alpha//sub 2/ remained constant and vice-versa. The J/sub cgb/ decreased exponentially with misorientation (/spl theta/). In addition, SEM studies showed that the boundaries meandered on the length scan of 0.5-2 /spl mu/m due to the island growth mode. The drop of J/sub cgb/ with increasing /spl alpha//sub 1/ and/or /spl alpha//sub 2/ is more than what can be explained by either the d-wave symmetry of its superconducting order parameters or boundary meandering.