Superconductor Science and Technology

Nonvolatile memory cell using a superconducting-ferromagnetic π Josephson junction

Junwen Zeng, Lei Chen, Xianghai Zhong, Yue Wang, Yinping Pan, Denghui Zhang, Shujie Yu, Ling Wu, Lu Zhang, Wei Peng, Zhen Wang

Published Jul 13, 2022• 9 citations

Publisher

Abstract

Abstract Storage of a single magnetic flux quantum in a superconducting loop containing a Josephson junction represents a promising unit cell configuration for construction of a cryogenic memory of superconducting digital circuits. However, application of a DC bias current is required for operation of such a memory cell to maintain trapping of the flux quantum in the storage loop. In this work, we present a superconducting memory cell that uses a superconducting-magnetic π junction. The cell characteristics show flux quantum hysteresis centering at the zero-bias current. We develop a fabrication process that combines superconductor–ferromagnet–superconductor (SFS) junctions with superconductor–normal metal–superconductor (SNS) junctions. The critical current density of the SFS junctions shows a 0–π oscillation as a function of the ferromagnetic layer thickness. The formation of the π junction is confirmed further by the flux modulation curves of a superconducting quantum interference device made from SNS junctions with an additional SFS junction.

DOI: 10.1088/1361-6668/ac80d9

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