ENGINEERED HTS MICROBRIDGES

In the absence of useful Josephson tunnel junctions made from cuprate superconductors, microbridges of various types are the only useful active devices for HTS electronics applications. A variety of techniques now exist to reproducibly engineer microbridges in high-quality epitaxial YBCO films. We report on two such techniques from our own group that have resulted in high-yield processes for fabricating both dc and rf SQUIDs operating at temperatures as high as 82 K. We compare the results on these devices - step-edge microbridges and focused-ion beam microbridges - with those on several other structures under investigation by other researchers.