Electrical properties of YBa/sub 2/Cu/sub 3/O/sub 7-x//PrBa/sub 2/Cu/sub 3/O/sub 7-x/ bi-layers

Abstract

The authors, investigated the electrical properties of YBa/sub 2/Cu/sub 3/O/sub 7-x/(YBCO)/PrBa/sub 2/Cu/sub 3/O/sub 7-x/(PBCO) bi-layers by fabricating YBCO/PBCO/Au/Nb junctions. For 5-nm-, 10-nm- and 20-nm-thick PBCO, supercurrents could be observed and uniformly distributed in the junction. The normal coherence length xi /sub n/ of PBCO was estimated to be 4 nm at 4.2 K from the relationship between I/sub c/R product and PBCO thickness. However, the junction resistance R was extremely small, compared with that of bulk PBCO for thicker PBCO. The temperature dependence of R posed the problem that a long-range interaction at least up to 300 nm existed between YBCO and PBCO below the critical temperature of YBCO in spite of the short coherence length xi /sub n/ of PBCO.< >