Transport properties of YBa2Cu3O7−δ/Y0.3Pr0.7Ba2Cu3O7−δ/YBa2Cu3 O7−δ Josephson junctions

Abstract

YBa2Cu3O7−δ/Y0.3Pr0.7Ba2Cu3O7−δ /YBa2Cu3O7−δ Josephson junctions have been prepared by a multistep laser ablation process using an improved shadow mask technique. Junctions with barrier layer thicknesses larger than 12 nm exhibit current-voltage characteristics which are close to those predicted by the resistively shunted junction (RSJ) model. Under microwave irradiation, clear Shapiro steps, which could be well described by the RSJ model, occur in the current-voltage curves. From the exponential decrease of the critical current density with increasing barrier layer thickness, an order parameter decay length ξn of 21±4 nm at T=4.2 K has been determined for Y0.3Pr0.7Ba2Cu3O7−δ. The increase of the junction resistance with decreasing temperature indicates that the barrier layer dominates the junction properties.