Josephson Current in Microbridges of YBa₂Cu₃O_7-δThin Films Prepared by CVD

Single crystallike microbridges are fabricated from YBa₂Cu₃O_7-δthin films made by the CVD method. The thicknesses of the bridges range from 0.2 to 1 µm, and the width and length are both about 1 µm. The critical current densities of the bridges range from 10⁴to 10⁵A/cm²at 77 K in zero field. The bridges show clear ac and dc Josephson effects. The single bridges look like typical Josephson junctions, and all transport current in the bridges behaves like Josephson current. However, the temperature dependences of critical current density show J_c∝(1-T/T_c)^3/2., the bridges behave like one-dimensional long superconductors.