Fabrication of S-N-S Josephson junctions of Y-Ba-Cu-O/Au/Nb thin film sandwiches

The authors have fabricated S-N-S Josephson junctions which consist of Y-Ba-Cu-O/Au/Nb thin film sandwiches with various thicknesses of Au barrier. Due to the ac-Josephson effect, the Shapiro steps are observed iin the S-N-S junctions under microwave radiation. The magnetic field dependence of the critical current shows that the junctions behave as the self-field limited Josephson junctions. In addition, from the temperature dependence of the critical current near the transition temperature of the junctions, it is found that the thickness of Au barrier is shorter than the coherence length of Au