Experimental analysis of superconducting properties of Y-Ba-Cu-O/Ag proximity interfaces

The electrical properties of YBa/sub 2/Cu/sub 3/O/sub 7-y//Ag proximity interfaces are reported. In order to study these properties, SNS (superconductor/normal metal/superconductor) junctions made of YBa/sub 2/Cu/sub 3/O/sub 7-y//Ag/Nb thin films and SNIS (superconductor/normal metal/insulator/superconductor) junctions made of YBa/sub 2/Cu/sub 3/O/sub 7-y//Ag/AlO/sub x//Nb thin films were examined. Experimental results on the SNS junctions imply that weak links are formed inside YBa/sub 2/Cu/sub 3/O/sub 7-y/ and that the junction properties depend on the area of the surface nonsuperconducting phases. The J/sub c/-R/sub n/ relationship and the R/sub n/-T characteristics suggest the presence of nonsuperconducting phases grown partially on the YBa/sub 2/Cu/sub 3/O/sub 7-y/ surfaces. The results on the SNIS junctions show little superconductivity induced in the Ag layers by the YBa/sub 2/Cu/sub 3/O/sub 7-y/ films.