Spin Triplet Supercurrent in Co/Ni Multilayer Josephson Junctions with Perpendicular Anisotropy

TL;DR

This study demonstrates the presence of spin-triplet supercurrent in Co/Ni multilayer Josephson junctions with perpendicular magnetic anisotropy, showing slow decay with layer thickness and potential for future superconducting spintronics.

Contribution

It provides experimental evidence of spin-triplet supercurrent in Co/Ni multilayer junctions with perpendicular anisotropy, highlighting the role of magnetization orthogonality and optimized critical current.

Findings

Supercurrent decays slowly with F-layer thickness

Supercurrent magnitude exceeds that in similar junctions without F' layers

Magnetic measurements confirm out-of-plane anisotropy

Abstract

We have measured spin-triplet supercurrent in Josephson junctions of the form S/F'/F/F'/S, where S is superconducting Nb, F' is a thin Ni layer with in-plane magnetization, and F is a Ni/[Co/Ni]n multilayer with out-of-plane magnetization. The supercurrent in these junctions decays very slowly with F-layer thickness, and is much larger than in similar junctions not containing the two F' layers. Those two features are the characteristic signatures of spin-triplet supercurrent, which is maximized by the orthogonality of the magnetizations in the F and F' layers. Magnetic measurements confirm the out-of-plane anisotropy of the Co/Ni multilayers. These samples have their critical current optimized in the as-prepared state, which will be useful for future applications.