Y₁Ba₂Cu₃O₇/MgO/Y ₁Ba₂Cu₃O₇ edge Josephson junctions

Josephson edge junctions have been fabricated using thin sputtered films of MgO (8-32 Å) to produce a weak connection between high Tc electrodes. The current voltage characteristics of these junctions can be well modeled by the resistively shunted junction (RSJ) equation and they possess excellent Josephson properties, exhibiting strong magnetic field modulation and microwave response at 10 and 100 GHz up to 82 K. The best high-temperature (T≳70 K) operation has been obtained with devices which have critical current densities in excess of 105 A/cm2 at 4.2 K, and junction critical current resistance products IcRn≅0. 15 mV at 60 K. Experiments indicate that improvements in device quality are expected as the base electrode junction surface is improved.