Characterization of a high temperature superconducting oxide thin-film RF SQUID

The authors have successfully fabricated and operated RF SQUIDs (superconducting quantum interference devices) made from thin films of the high-temperature superconducting oxide ErBa/sub 2/Cu/sub 3/O/sub 7-x/. The ideal triangular quantum interference pattern characteristics of RF SQUIDs are observed. The performance of a particular device, operating between 60 and 65 K, is described in detail. Except for a possible increase of noise due to operation close to T/sub c/, the limited temperature range is shown to have no decisive practical disadvantage. The precise nature of the Josephson coupling in the device is unclear. It seems likely that Josephson coupling occurs between individual grains and probably within the microbridge.<
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