Magnetic Josephson Junctions on Nb Four-layer Structure for Half Flux Quantum Circuits

Abstract

We successfully fabricated magnetic Josephson junctions integrated on a Nb four-layer superconducting structure for demonstrating half flux quantum (HFQ) circuits. In the developed process, we adopted a $0-0-\pi$ SQUID instead of the $0-\pi$ SQUID as the basic element of the HFQ circuits. In this work, we characterized the Nb/PdNi/Nb magnetic Josephson junctions on the Nb four-layer structures fabricated by two different processes. We measured the I-V characteristics of junctions in liquid helium at 4.2 K. The results showed that the fabricated junctions had properties comparable to conventional ones on Si wafers.