Sensitive high-T/sub c/ SQUID magnetometers for unshielded operation

Author

Dilorio, M.S. ; Yang, K. ; Yoshizumi, S. ; Haupt, S.G. ; Haran, D. ; Koch, R.H. ; Milliken, F.P. ; Rozen, J.R. ; Lathrop, D.K. ; Kumar, S. ; Trammell, H.S., III

Author_Institution

Magnesensors Inc., San Diego, CA, USA

Volume

9

Issue

2

fYear

1999

fDate

6/1/1999 12:00:00 AM

Firstpage

4428

Lastpage

4431

Abstract

We have developed sensitive highly reliable high-T/sub c/ SQUID magnetometers a reproducible SNS junction fabrication process. In order to enable unshielded operation in the earth´s field, we have incorporated flux dams into direct-coupled SQUID magnetometers. By using up to four pickup coils in parallel, each with its own flux dam, an effective area of 0.57 mm/sup 2/ has been achieved on 24 mm/spl times/24 mm substrates using 100 /spl mu/m wide pickup coils. We have demonstrated a magnetic field noise sensitivity of 80 fT//spl radic/Hz 10 Hz and 77 K in an externally applied field 60 /spl mu/T. This magnetic field sensitivity unchanged from the zero-field measurement.

Keywords

SQUID magnetometers; high-temperature superconductors; superconductor-normal-superconductor devices; 10 Hz; 60 muT; 77 K; SNS junction fabrication; SQUID magnetometer; direct coupling; flux dam; high-T/sub c/ superconductor; magnetic field noise sensitivity; pickup coil; unshielded operation; Degradation; Inductance; Low-frequency noise; Magnetic field measurement; Magnetic fields; Magnetic noise; SQUID magnetometers; Superconducting coils; Superconducting device noise; Working environment noise;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.784007

Filename

784007