High-T/sub c/ SQUIDS with local oxygen-ion irradiated weak links

High-T/sub c/ S-N-S RF superconducting quantum interference devices (SQUIDs) were successfully made from single-layer high-quality epitaxial YBCO films. These SQUIDS operate at liquid nitrogen temperature using local oxygen-ion irradiated microbridges. Device yields of about 70% have been obtained with preamplifier limited noise properties. Microbridges of this type can be used as active devices also for other electronic applications because only standard integrated circuit techniques are needed. The magnetic field sensitivity of the 1.4-mm*1.4-mm SQUID is 2 pT Hz/sup -1/2/ at 10 Hz. A parallel connected 8-mm*8-mm pick-up loop improves the sensitivity of 0.7 pT Hz/sup -1/2/.>