Theoretical Model of Superconducting Spintronic SIsFS Devices

Abstract

Motivated by recent progress in development of cryogenic memory compatible with single flux quantum (SFQ) circuits we have performed a theoretical study of magnetic SIsFS Josephson junctions, where 'S' is a bulk superconductor, 's' is a thin superconducting film, 'F' is a metallic ferromagnet and 'I' is an insulator. We calculate the Josephson current as a function of s and F layers thickness, temperature and exchange energy of F film. We outline several modes of operation of these junctions and demonstrate their unique ability to have large product of a critical current $I_C$ and a normal-state resistance $R_N$ in the $\pi$ state, comparable to that in SIS tunnel junctions commonly used in SFQ circuits. We develop a model describing switching of the Josephson critical current in these devices by external magnetic field. The results are in good agreement with the experimental data for Nb-Al/AlO${}_x$-Nb-Pd${}_{0.99}$Fe${}_{0.01}$-Nb junctions.

10 pages, 5 figures, accepted to Applied Physics Letters

References in corpus (2)

• Ferromagnetic Josephson switching device with high characteristic voltage
• Magnetic-coupling-dependent spin-triplet supercurrents in helimagnet/ferromagnet Josephson junctions

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