FLUX COUPLING IN THE DIRECT-COUPLED HIGH-T-C SUPERCONDUCTING QUANTUM INTERFERENCE DEVICES

We have fabricated high-T-c dc superconducting quantum interference de vices (SQUIDs), which have different geometries of the hole and config urations of current injection leads, in the direct-coupling magnetomet er, and measured the coupling efficiency of the flux generated by the injected current. It has been found that the coupling is efficient in the case where the current flows uniformly across the width of the pat h around the SQUID hole. High coupling of more than 80% was obtained i n a geometry of narrow parallel strips with wide slit of the SQUlD hol e between them.