Development of Low-Noise Step-Edge Junctions for High Tc Squid Applications

Although significant progress has been made in the fabrication of high quality high temperature superconducting (HTS) thin films over the past few years, several materials and processing issues still need to these films can be possible. This research is directed toward the development of HTS thin films with improved flux noise and critical current properties for operation in liquid nitrogen at 77K. A specific goal is the fabrication of low-noise step-edge Josephson junctions for use in high-Tc direct current magnetometers. In Phase I innovative substitutions in YBa2Cu307-x epitaxial thin films will be investigated to demonstrate improved levels of low frequency noise in substituted thin films, and the characteristics of step-edge junctions developed from such films will be evaluated. The ultimate goal of Phase II is to build low-noise high Tc SQUID magnetometers down to low frequencies. The proposed work will be performed by Quantum Magnetics in collaboration with a research group at the University of California San Diego. Significant support will also be provided by IBM Research.