Amplitude control of spin-triplet supercurrent in S/F/S Josephson junctions

TL;DR

This paper demonstrates control over spin-triplet supercurrent in S/F/S Josephson junctions by rotating magnetization, confirming theoretical predictions and advancing superconducting spintronics applications.

Contribution

It provides experimental evidence for on-off control of spin-triplet supercurrent via magnetization rotation in multi-layer ferromagnetic Josephson junctions.

Findings

Achieved on-off supercurrent ratios of 5, 7, and 19.

Confirmed the prediction that orthogonal magnetizations maximize triplet supercurrent.

Demonstrated potential for superconducting spintronics applications.

Abstract

Josephson junctions made with conventional s-wave superconductors and containing multiple layers of ferromagnetic materials can carry spin-triplet supercurrent in the presence of certain types of magnetic inhomogeneity. In junctions containing three ferromagnetic layers, the triplet supercurrent is predicted to be maximal when the magnetizations of adjacent layers are orthogonal, and zero when the magnetizations of any two adjacent layers are parallel. Here we demonstrate on-off control of the spin-triplet supercurrent in such junctions, achieved by rotating the magnetization direction of one of the three layers by 90$^{\circ}$. We obtain "on-off" ratios of 5, 7, and 19 for the supercurrent in the three samples studied so far. These observations directly confirm one of the most salient predictions of the theory, and pave the way for applications of spin-triplet Josephson junctions in the nascent area of "superconducting spintronics."