Low noise YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} SQUID magnetometers operated with additional positive feedback
- Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany)
- Department of Physics, University of California, Berkeley
- Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg (Germany)
- Philips Research Laboratories, Dept. Technical Systems, Roentgenstrasse 24-26, 22335 Hamburg (Germany)
Three magnetometers based on dc superconducting quantum interference devices (SQUIDs) fabricated from YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} have been operated in a magnetically shielded room using a flux-locked loop involving additional positive feedback with bias current reversal. Two of these devices, integrated multiloop dc SQUIDs with outer diameters of 7 mm, achieved white noise levels of 10 fT/{radical}Hz for bicrystal junctions and 30 fT/{radical}Hz for step-edge junctions. The third magnetometer involved a flux transformer with a 10{times}10 mm{sup 2} pickup coil connected to a 16-turn input coil which was inductively coupled to a bicrystal SQUID. This device achieved a white noise of 16.2 fT/{radical}Hz. High quality magnetocardiograms were obtained without signal averaging. {copyright} {ital 1996 American Institute of Physics.}
- Research Organization:
- Lawrence Berkeley National Laboratory
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 279716
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 13 Vol. 68; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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