SNS-DC-SQUIDs and flux transformers for integrated magnetometers in flip-chip technique

SNS-direct current-superconducting quantum interference devices (DC-SQUIDs) with a step-and-gap geometry are fabricated by preparing YBCO/Ag/YBCO-Josephson junctions across steps in MgO substrates. An additional etching process is employed to remove the unwanted shunt resistance on top of the YBCO films. Transverse electromagnetic examinations show that this approach improves the DC-SQUIDs' normal resistance without any reduction of the critical current.