Journal article

Integrated high-T/sub c/ SQUID magnetometer

We have fabricated an integrated SQUID magnetometer based on Y/sub 1/Ba/sub 2/Cu/sub 3/O/sub 7/ step-edge Josephson junctions. A tight coupling between the input coil and the SQUID washer has been achieved with a coupling coefficient K of 0.9. Noise measurements on our SQUIDs showed a nearly frequency independent flux noise of 50 /spl mu//spl Phi//sub 0///spl radic/Hz at 77 K. 1/f-noise contributions at lower temperatures were always completely suppressed by bias reversal. From our measurements of the field sensitivity and the flux noise we can estimate a field resolution of the magnetometer of 60 fT//spl radic/Hz down to 1 Hz.textlesstextgreater


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