Temperature dependence and magnetic field modulation of critical currents in step-edge SNS YBCO/Au junctions

We compare the electrical transport properties of superconductor-normal metal-superconductor SNS step-edge YBCO/Au junctions where the Au is deposited at 100/spl deg/C and 600/spl deg/C. For both types of junctions we observe resistively shunted junction current-voltage characteristics. The critical currents I/sub c/ in all cases are similar for a given ratio of YBCO thickness-to-step height, while the normal resistance R/sub n/ for the Au deposited at 600/spl deg/C is consistently 25% lower than for the Au deposited at 100/spl deg/C. The normalized temperature dependence of the I/sub c/R/sub n/ product is nearly identical for all junctions with Au deposited at high temperatures but varies among junctions on a single chip for Au deposited at 100/spl deg/C. Low magnetic field modulation of the critical current can show either the expected Fraunhofer-like pattern or a double-junction modulation for both types of devices. The modulation period is consistently a factor of 3 lower for the high-temperature deposited Au.<
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