Title :
Materials issues related to the fabrication of HTS SQUIDs
Author :
Haupt, S.G. ; Lathrop, D.K. ; Matthews, R. ; Brown, S.L. ; Altman, R. ; Gallagher, W.J. ; Milliken, F. ; Sun, J.Z. ; Koch, R.H.
Author_Institution :
Quantum Magnetics, San Diego, CA, USA
fDate :
6/1/1997 12:00:00 AM
Abstract :
A number of materials related problems have hindered the development of a reproducible process for the fabrication of high-quality SQUIDs and magnetometers. In this paper we discuss the use of GdBa/sub 2/Cu/sub 3/O/sub 7/ and YBa/sub 2/Cu/sub 3/O/sub 7/ thin films for the fabrication of step-edge and bicrystal magnetometers and how materials selection can influence issues such as reproducibility, yield and noise performance. Magnetometers with noise performance as low as 63 fT//spl radic/Hz have been made with variations in junction parameters (I/sub c/ and R/sub n/) that are as low as 25% on-chip and 57% from chip-to-chip.
Keywords :
SQUID magnetometers; barium compounds; bicrystals; critical currents; gadolinium compounds; grain boundaries; high-temperature superconductors; superconducting device noise; superconducting device testing; yttrium compounds; GdBa/sub 2/Cu/sub 3/O/sub 7/; GdBa/sub 2/Cu/sub 3/O/sub 7/ thin films; HTS SQUID fabrication; YBa/sub 2/Cu/sub 3/O/sub 7/; YBa/sub 2/Cu/sub 3/O/sub 7/ thin films; bicrystal magnetometers; flux noise; grain boundary junctions; junction parameter variations; materials issues; materials selection; noise performance; reproducible process; step-edge magnetometers; yield; Fabrication; Grain boundaries; High temperature superconductors; Josephson junctions; Magnetic materials; Reproducibility of results; SQUID magnetometers; Substrates; Superconducting epitaxial layers; Superconducting films;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
