Abstract
Abstract The superconducting proximity effect can be used to produce Josephson junctions in HTS structures with a normal conducting barrier. We describe a work on "break-film" junctions made by Au bridge to link the upper and lower layer of a YBa2Cu3O7(YBCO)-SrTiO3(STO)-YBa2Cu3O7 (YBCO) trilayer. The structures are grown in situ by pulse laser deposition. In our early structure we observed no supercurrent. That is because the exposure of the film in air before N-layer evaporation gives rise to an interface potential barrier. When T increases from 4.2K, the gap feature broadens until it is barely resolved around 65K. Such behavior is in general agreement with the BTK theory. We observed zero-bias anomaly (ZBA) spectra in some of our "break-film" junctions, which can also be explained by the BTK theory with the s-wave symmetry of the superconducting order parameter of YBCO. Our junction has a critical current density about 1.6*104 A/cm2 at 4.2K, IcR-n=0.125mV. The characteristic of the junction implies a high potential for applications.