High-T/sub c/ multilayer magnetometers with improved 1/f noise

We have fabricated three types of high T/sub c/ magnetometers using a YBa/sub 2/Cu/sub 3/O/sub 7-x/-SrTiO/sub 3/-YBa/sub 2/Cu/sub 3/O/sub 7-x/, multilayer process: multiturn flux transformers coupled to single layer dc SQUIDs in a flip-chip arrangement, multiturn flux transformers integrated with dc SQUIDs, and multiloop magnetometers (fractional turn SQUIDs). The magnetic field noise of the best flip-chip magnetometer was 74 fTHz/sup -1/2/ at 1 Hz and 31 fTHz/sup -1/2/ at 1 kHz. The magnetic field noise of the multiloop magnetometer, measured in a YBCO tube, was 37 fTHz/sup -1/2/ at 1 Hz and 18 fTHz/sup -1/2/ at 1 kHz.<
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