Topological magnons with nodal-line and triple-point degeneracies: Implications for thermal Hall effect in pyrochlore iridates

TL;DR

This paper investigates topological magnon excitations in pyrochlore iridates with all-in-all-out order, revealing how their unique band crossings influence the thermal Hall effect, and identifying regimes of topological magnon band structures.

Contribution

It uncovers the topological features of magnon bands in pyrochlore iridates and links these features to observable thermal Hall responses.

Findings

Identification of nodal-line and triple-point degeneracies in magnon bands.

Three regimes of magnon band topology based on Dzyaloshinskii-Moriya interaction ratio.

Thermal Hall effect as a probe of topological magnon band structures.

Abstract

We analyze the magnon excitations in pyrochlore iridates with all-in-all-out (AIAO) antiferromagnetic order, focusing on their topological features. We identify the magnetic point group symmetries that protect the nodal-line band crossings and triple-point degeneracies that dominate the Berry curvature. We find three distinct regimes of magnon band topology, as a function of the ratio of Dzyaloshinskii-Moriya (DM) interaction to the antiferromagnetic exchange. We show how the thermal Hall response provides a unique probe of the topological magnon band structure in AIAO systems.