Properties of all YBa2Cu3O7 Josephson edge junctions prepared by in situ laser ablation deposition

Thin-film YBa2Cu3O7-YBa2Cu3O7 edge junctions of 0.4×10 μm2 cross section were prepared in situ by a multistep laser ablation deposition process. The fabrication time was about 3 h and the yield of good devices was 50%. Typical junctions reached zero resistance at 72 K and had a critical current density Jc of 300 A/cm2 at 70 K. Their Jc as a function of temperature increased slowly with decreasing temperature down to 65 K and much faster below it. In the region of low Jc we observed suppression of the critical current by a magnetic field. Under microwave radiation clear Shapiro steps were observed whose magnitude versus the microwave field agreed qualitatively with the resistively shunted junction model of a current biased junction.