Magnon-induced transparency of a disordered antiferromagnetic Josephson junction

TL;DR

This paper demonstrates that magnons in a disordered antiferromagnetic metal can significantly enhance Josephson currents in long superconducting junctions, revealing a new magnon-induced transparency effect with potential spintronics applications.

Contribution

It introduces the concept of magnon-induced enhancement of Josephson currents in disordered AFM-based junctions, expanding understanding of superconducting proximity effects in magnetic materials.

Findings

Magnons can strongly enhance Josephson currents in long AFM junctions.

The effect persists for junctions comparable to the superconducting coherence length.

Magnon interactions significantly influence superconducting proximity effects in AFM materials.

Abstract

We considered a planar Josephson junction which is composed of two s-wave superconducting contacts deposited on the top of a thin antiferromagnetic (AFM) disordered metal film. In such a system noticeable Josephson currents may be observed, if contacts are just nanometers away from each other. It is shown that the excitation of AFM by magnons results in a strong enhancement of the stationary current through much longer junctions, whose length may be comparable to the coherence length of superconducting correlations in a nonmagnetic metal. Such a current is calculated at the weak tunneling amplitude of electrons between superconducting contacts and AFM. The problem is considered for nonequilibrium Green functions in the second-order perturbation theory with respect to the electron-magnon interaction. A spin-orbit torque oscillator was taken as a possible source of long-wavelength classic magnetic waves. This work predicts a strong effect of magnons on superconducting proximity effect in AFM, with promising applications in superconducting spintronics.