Ferromagnetic Josephson memory elements with perpendicular magnetic anisotropy

Traditionally considered competing phenomena, when artificially juxtaposed a wealth of new physics at the interface between superconductors and ferromagnets emerges. By combining ferromagnetism with the dissipationless property of superconductivity, superconducting spintronic memory and logic devices have potential to be both fast and highly energy efficient.

Here, I will describe the fabrication and characteristics of S—F—S Josephson devices, where the ferromagnetic barriers have perpendicular magnetic anisotropy (PMA), which provides distinct advantages over systems with in-plane magnetizations [1,2]. I will present a PMA spin-valve device, where magnetic multilayers of Pt/Co/Pt and Pt/CoB/Pt have interfacial PMA and independent switching fields, allowing the device to be configured into parallel and antiparallel magnetic configurations. By tuning the magnetic configuration, we report that the critical supercurrent in the device can be tuned by 60% [1]. Finally, I will discuss our progress towards fabricating epitaxial Josephson junctions using ferromagnetic compounds with intrinsic PMA.

[1] N. Satchell, et al. Appl. Phys. Lett. 116, 022601 (2020)

[2] N. Satchell, et al. Sci. Rep. 11, 11173 (2021)