Fabrication of ramp-edge junction with NdBa2Cu3Oy-based interface-modifiedbarrier

We report on the first successful fabrication of ramp-edge junctions with a n NdBa2Cu3Oy (NBCO)-based interface-modified barrier in which a YBa2Cu3Oy ( YBCO) film is employed as a counterelectrode. The interface-modified barrie r on the NBCO ramp surface is formed by electron cyclotron resonance (ECR) ion etching and subsequent annealing treatments to the ramp surface. By ann ealing at a slightly higher temperature than that for a YBCO-based interfac e-modified barrier just before counterelectrode growth, resistively shunted junction type current-voltage (I-V) characteristics with the IcRn product at 4.2 K of approximately 1.6 mV are obtained. These results suggest that N BCO as well as YBCO can be used in high-quality ramp-edge junctions.