The variation of J _cgb with GB misorientation and inclination measured using the Scanning SQUID Microscope

Abstract

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