Development of ramp-edge SNS Josephson junctions and SQUIDs

We have fabricated high performance Josephson junctions, dc SQUIDs, and directly-coupled SQUID magnetometers, where the junction uses a ramp-edge superconductor/normal-metal/superconductor (SNS) configuration. The devices are fully defined by the standard photolithography. We use Ag-doped YBa2Cu3O7−x for the superconducting electrodes and PrBa2Cu3O7−x as the N-layer barrier. The controllability of the processing and the reproducibility of the device performance was improved substantially by using Ag-doped YBa2Cu3O7−x for the electrodes.