Enhancement of Josephson Supercurrent in a $\pi$-Junction state by Chiral Antiferromagnetism

TL;DR

This paper demonstrates that chiral antiferromagnetism can significantly enhance Josephson supercurrents by promoting equal-spin triplet pairing, leading to stable $$-junction states in magnetic Josephson junctions.

Contribution

It reveals a novel mechanism where chiral antiferromagnetism enhances supercurrent via triplet pairing, contrasting with typical magnetic suppression of superconductivity.

Findings

Chiral antiferromagnetism induces dominant equal-spin triplet pairing.

Enhanced supercurrent remains stable across various energies, temperatures, and junction lengths.

The phenomena are demonstrated in kagome lattice-based Josephson junctions.

Abstract

Magnetic order typically disrupts superconductivity, reducing the supercurrent. Here, we show that chiral antiferromagnetism, with non-relativistic spin-split bands and distinctive valley-locked spin texture, can instead significantly enhance Josephson supercurrents. This enhancement stems from the emergence of dominant equal-spin triplet pairing and strong fluctuations of singlet pairing in momentum space, both induced by chiral antiferromagnetism. We demonstrate these results in Josephson junctions composed of chiral antiferromagnetic metals and conventional superconductors on kagome lattices. Furthermore, we show that the enhanced Josephson supercurrent is stabilized in a $\pi$-junction state. These phenomena persist across a broad energy range and remain stable for different temperatures and junction lengths. Our results unveil a previously unexplored mechanism for enhancing supercurrent by strong magnetic order and provide crucial insights into the large Josephson currents observed in Mn$_3$Ge.