Study of DyBaCuO DC SQUIDs for low noise and high flux focusing

We have fabricated DyBaCuO DC SQUIDs by MBE growth on MgO substrates containing 45/spl deg/ step-edge Josephson junctions. They showed RSJ-like current-voltage characteristics and periodic modulation of voltage aroused by an applied magnetic field at 77 K. The flux resolution of the 1.9 mm square washer SQUID was measured to 3/spl times/10/sup -4/ /spl Phi//sub 0//Hz/sup 1/2/ at 1 Hz, which corresponds to a magnetic field sensitivity of 14 pT/Hz/sup 1/2/. Effective flux capture areas were investigated for varying SQUID size of washer and hole. >