TEMPERATURE-DEPENDENCE AND MAGNETIC-FIELD MODULATION OF CRITICAL CURRENTS IN STEP-EDGE SNS YBCO AU JUNCTIONS/

We compare the electrical transport properties of superconductor-norma l metal-superconductor SNS step-edge YBCO/Au junctions where the Au is deposited at 100 degrees C and 600 degrees C. For both types of junct ions we observe resistively shunted junction current-voltage character istics. The critical currents I-c in all cases are similar for a given ratio of YBCO thickness-to-step height, while the normal resistance R (n) for the Au deposited at 600 degrees C is consistently 25% lower th an for the Au deposited at 100 degrees C. The normalized temperature d ependence of the I(c)R(n) product is nearly identical for all junction s with Au deposited at high temperatures but varies among junctions on a single chip for Au deposited at 100 degrees C. Low magnetic field m odulation of the critical current can show either the expected Fraunho fer-like pattern or a double-junction modulation for both types of dev ices. The modulation period is consistently a factor of 3 lower for th e high-temperature deposited Au.