CURRENT RESOLUTION, NOISE, AND INDUCTANCE MEASUREMENTS ON HIGH-T-C DCSQUID GALVANOMETERS

Single layer autonomous high-T-c de superconducting quantum interferen ce devices (SQUIDs) have been fabricated and tested. The SQUIDs were d esigned for application as a galvanometer. The current to be measured is injected directly in a microstrip segment of the SQVID loop. Step-e dge as well as bicrystal YBCO Josephson junctions were used. We consid er two aspects: (i) optimization of the noise properties with respect to current resolution, and (ii) temperature dependence of the period o f voltage-flux relation. The SQUID inductance was calculated numerical ly taking into account the magnetic field penetration depth lambda. Th e temperature dependence of lambda(T) was obtained from experimental r esults and is found to be in good agreement with lambda(T)approximate to(0) X[1-(T/T-C)(2)](-1/2). (C) 1996 American Institute of Physics.