Multilayer superconducting devices made using biepitaxial grain boundary Josephson junctions in YBa2Cu3O7

摘要

We will report advances in superconducting devices and circuits made using bi-epitaxial grain boundary Josephson junctions in YBa$-2$/Cu$-3$/O$-7$/. These bi-epitaxial grain boundary junctions are created at predetermined locations by controlling the in-plane epitaxy of YBa$-2$/Cu$-3$/O$-7$/ with a seed layer and a buffer layer on a base layer. SQUIDs made from these junctions show modulation up to 88 K and their white noise level is at the theoretical limit. Complete magnetometers coupled with multi-turn flux transformers made using multi-layer technology have magnetic field sensitivity at 77 K sufficient to be useful for many applications. Our recent success in fabricating integrated SQUIDs by combining the SQUID and multi-turn flux transformer on a single substrate is described. Low level integrated circuits with tens of bi-epitaxial grain boundary Josephson junctions have been fabricated. The current status of these circuits is reported.