Spin-valve Josephson junctions with perpendicular magnetic anisotropy for cryogenic memory

TL;DR

This paper presents a Josephson junction with a weak link containing two perpendicular magnetic anisotropy ferromagnets, enabling critical current control via magnetic orientation, advancing cryogenic memory technology.

Contribution

It introduces a pseudospin-valve Josephson junction with perpendicular magnetic anisotropy, demonstrating significant critical current modulation for cryogenic memory applications.

Findings

Achieved 60% change in critical current between magnetic states.

Used Pt/Co/Pt/CoB/Pt as the weak link with specified thicknesses.

Ferromagnets with perpendicular anisotropy offer advantages over in-plane systems.

Abstract

We demonstrate a Josephson junction with a weak link containing two ferromagnets, with perpendicular magnetic anisotropy and independent switching fields in which the critical current can be set by the mutual orientation of the two layers. Such pseudospin-valve Josephson junctions are a candidate cryogenic memory in an all superconducting computational scheme. Here, we use Pt/Co/Pt/CoB/Pt as the weak link of the junction with $d_\text{Co} = 0.6$ nm, $d_\text{CoB} = 0.3$ nm, and $d_\text{Pt} = 5$ nm and obtain a $60\%$ change in the critical current for the two magnetization configurations of the pseudospin-valve. Ferromagnets with perpendicular magnetic anisotropy have advantages over magnetization in-plane systems which have been exclusively considered to this point, as in principle the magnetization and magnetic switching of layers in the junction should not affect the in-plane magnetic flux.