Vertical c-axis microbridge junctions in YBa/sub 2/Cu/sub 3/O/sub 7//PrBa/sub 2/Cu/sub 3/O/sub 7/ thin films

The fabrication and measurement of microbridge junctions in the vertical c-axis direction of YBCO/PBCO/YBCO evaporated thin films is described. Single junctions show critical current modulation with applied magnetic field, the period scaling with junction size. The IV characteristics show Shapiro steps to high order when irradiated with microwaves. Initial measurements of linear arrays suggest that with further optimisation of the processing steps a reproducible junction technology could emerge. Very low inductance (L/spl ap/5-15 pH) SQUIDs have been demonstrated with dV/d/spl Phi/>1 mV//spl Phi//sub 0/ at 50 K. The vertical SQUID loop geometry of these SQUIDs has allowed a direct determination of the penetration depth as a function of temperature.<
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