Superconductor–normal–superconductor Josephson junctions fabricated by oxygen implantation into YBa2Cu3O7−δ

Abstract

We report Josephson junctions in YBa2Cu3O7−δ films, fabricated by oxygen irradiation through a 50 nm wide slit in an implantation mask. After annealing the irradiated microbridges at 500 °C in an oxygen atmosphere, this process creates a homogeneous barrier region with a reduced but finite transition temperature, allowing Josephson coupling in a temperature window of ⩽15 K. Over the entire temperature range of Josephson coupling these junctions show resistively shunted junction behavior. The exponential dependence of the critical current on temperature is in good agreement with conventional superconductor–normal–superconductor proximity effect theory.