Investigation of flux trapping into moats with various moat depths by a scanning SQUID microscope

摘要

We have observed flux trapping in high-T-c thin films with moats fabricated by focused Ga ion beam etching using a scanning SQUID microscope (SSM) system. Flux exclusion effect was investigated for moats or moat patterns with various moat depths on a 190-nm-thick NdBa2Cu3Oy (NBCO) sputtered thin film and a 120-nm-thick La0.2Y0.9Ba1.9Cu3Oy (La-YBCO) sputtered thin film. It was found that magnetic flux can be trapped into a moat with a moat depth smaller than the film thickness. In addition, we confirmed that the array of 136-mum-long and 4-mum-wide moats certainly suppress flux trapping inside the moat-surrounded 160 x 160 mum(2) area even when its moat depth is only 19% of the film thickness of 190 nm. (C) 2003 Elsevier B.V. All rights reserved. [References: 5]