A new concept for integrated YBa/sub 2/Cu/sub 3/O/sub 7/ magnetometers

Author

Scharnweber, R. ; Schilling, M.

Author_Institution

Inst. fur Angewandte Phys., Hamburg Univ., Germany

Volume

7

Issue

2

fYear

1997

fDate

6/1/1997 12:00:00 AM

Firstpage

3485

Lastpage

3488

Abstract

We present an integrated magnetometer concept that combines inductance matching by a flux transformer with the low inductance of a multiloop pick-up coil. Using ramp-type Josephson junctions with PrBa/sub 2/Cu/sub 3/O/sub 7/ barriers, a 90 pH dc SQUID together with a five turn flux transformer is coupled to a multiloop pick-up coil. The dependence of the effective area of the magnetometer on the temperature is investigated by successively disconnecting the pick-up loops. The 1/f flux noise of the integrated magnetometer is suppressed by operation in a flux-locked loop mode with bias current modulation. This results in a flux density noise of /spl radic/(S/sub B/)(1 Hz,77 K)=100 fT//spl radic/(Hz). Using this magnetometer, different biomagnetic measurements have been performed.

Keywords

1/f noise; Josephson effect; SQUID magnetometers; barium compounds; biomagnetism; flux flow; high-temperature superconductors; inductance; superconducting device noise; yttrium compounds; 1/f flux noise; YBa/sub 2/Cu/sub 3/O/sub 7/-PrBa/sub 2/Cu/sub 3/O/sub 7/; bias current modulation; biomagnetic measurements; dc SQUID; flux density noise; flux transformer; flux-locked loop mode; inductance matching; integrated magnetometer; multiloop pick-up coil; ramp-type Josephson junctions; Acoustical engineering; Coils; Inductance; Josephson junctions; Magnetic flux; Magnetic modulators; Magnetic noise; SQUID magnetometers; Superconducting device noise; Superconducting magnets;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.622144

Filename

622144