Nonlinear hysteresis in thin film SQUID magnetometers

Author

Sun, J.Z. ; Gallagher, W.J. ; Koch, R.H.

Author_Institution

IBM Thomas J. Watson Res. Center, Yorktown Heights, NY, USA

Volume

3

Issue

1

fYear

1993

fDate

3/1/1993 12:00:00 AM

Firstpage

2022

Lastpage

2025

Abstract

Measurements on both YBaCuO- and Nb-based thin-film DC superconducting quantum interference device (SQUID) magnetometers reveal a nonlinear hysteresis at fields above 0.1 G. The nonlinear hysteresis is sensitive to sample temperature but insensitive to the time scale of the field sweep in the millisecond region. Such hysteresis can be accounted for by the nucleation and subsequent displacement of vortices at the edges of the SQUID input washer. A model has been developed that relates hysteresis to film current density. The model predicts an asymptotic quadratic field dependence, quantitatively consistent with the present data, and also predicts a threshold field which is suggested by the data.<>

Keywords

SQUIDs; barium compounds; flux flow; high-temperature superconductors; magnetic hysteresis; magnetometers; niobium; yttrium compounds; HTSC; Nb; YBaCuO; asymptotic quadratic field dependence; displacement of vortices; film current density; model; nonlinear hysteresis; thin film SQUID magnetometers; threshold field; vortices nucleation; Hysteresis; Interference; Magnetic field measurement; SQUID magnetometers; Superconducting devices; Superconducting thin films; Temperature sensors; Thin film devices; Time measurement; Transistors;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.233460

Filename

233460