PROXIMITY EFFECT IN YBA2CU3O7-DELTA/YBA2(CU1-XCOX)(3)O-7-DELTA-3/YBA2CU3O7-DELTA JUNCTIONS - FROM THE CLEAN LIMIT TO THE DIRTY LIMIT WITH PAIR-BREAKING

We report on the proximity effect observed in YBa2Cu3O7-δ/YBa2(Cu1- xCox)3O7-δ /YBa2Cu3O7-δ junctions in an edge-junction geometry where x=0.04, 0.07, and 0.14. The temperature, thickness, and doping dependence of the critical current of the junctions can be well described by the proximity-effect theory, due to very little interface resistance. We observed a crossover from the clean limit to the dirty limit behavior where a pair-breaking scattering time τpb=6×10-14 sec, consistent with short-range magnetic fluctuations in the barrier, was found. © 1995 The American Physical Society.