Chiral topological insulator of magnons

TL;DR

This paper introduces a 3D topological insulator model for magnons with chiral symmetry, demonstrating topological surface states, protected Dirac cones, and tunable phase transitions between different magnon topological phases.

Contribution

It presents a novel magnon-based realization of 3D chiral topological insulators, including the calculation of topological invariants and analysis of surface magnon modes.

Findings

Topological magnon gap opens via Dzyaloshinskii-Moriya interactions.

Surface magnon Dirac cones are protected by chiral symmetry.

System can be tuned between different topological magnon phases.

Abstract

We propose a magnon realization of 3D topological insulator in the AIII (chiral symmetry) topological class. The topological magnon gap opens due to the presence of Dzyaloshinskii-Moriya interactions. The existence of the topological invariant is established by calculating the bulk winding number of the system. Within our model, the surface magnon Dirac cone is protected by the sublattice chiral symmetry. By analyzing the magnon surface modes, we confirm that the backscattering is prohibited. By weakly breaking the chiral symmetry, we observe the magnon Hall response on the surface due to opening of the gap. Finally, we show that by changing certain parameters the system can be tuned between the chiral topological insulator (mcTI), three dimensional magnon anomalous Hall (3D-mAH), and Weyl magnon phases.