INTEGRATED HIGH T-C SQUID MAGNETOMETER

We have fabricated an integrated SQUID magnetometer based on Y1Ba2Cu3O 7 step-edge Josephson junctions. A tight coupling between the input co il and the SQUID washer has been achieved with a coupling coefficient k of 0.9. Noise measurements on our SQUIDs showed a nearly frequency i ndependent flux noise of 50 mu Phi(0)/root Hz at 77 K. 1/f-noise contr ibutions at lower temperatures were always completely suppressed by bi as reversal. From our measurements of the field sensitivity and the fl ux noise we can estimate a field resolution of the magnetometer of 60 fT/root Hz down to 1 Hz.