Single layer YBa2Cu3O7 radio frequency SQUID magnetometers with direct-coupled pickup coils and flip-chip flux transformers
- 26 December 1994
- journal article
- conference paper
- Published by AIP Publishing in Applied Physics Letters
- Vol. 65 (26) , 3380-3382
- https://doi.org/10.1063/1.112398
Abstract
Our aim has been to further improve the magnetic field resolution, BN, of single‐layer rf SQUID magnetometers operating in liquid nitrogen. Following the approaches recently introduced in dc SQUIDs, we tested designs with direct‐coupled pickup coils having an area Ap=0.6 to 0.8 cm2, and a single‐layer thin‐film flip‐chip flux transformer with Ap=16 cm2. In conditions of still suboptimal coupling between SQUID and the 150 MHz tank circuit, we attained BN≂90 fT/Hz1/2 above 3–4 Hz at Ap=0.8 cm2, and BN≂24 fT/Hz1/2 above 0.5 Hz when Ap=16 cm2. For rf SQUID with lumped‐element tank circuit, we project the lower BN limit to be ≤50 fT/Hz1/2 at Ap≤1 cm2. This might be attainable through further coupling optimization, and increase of tank frequency to the highest possible value of ≥500 MHz.Keywords
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