# Symmetry-protected topological magnons in three dimensional Kitaev materials

## TL;DR

This paper explores how three-dimensional Kitaev materials can host symmetry-protected topological magnons, revealing unique topological features and control mechanisms in magnetic systems with potential applications in quantum materials.

## Contribution

It demonstrates the existence of symmetry-protected topological magnons in 3D Kitaev materials and analyzes their unique topological protection due to magnetic symmetries and non-Hermitian properties.

## Key findings

- Identification of topological magnons in hyperhoneycomb $eta$-Li2IrO3
- Magnetic glide symmetries protect topological features
- Control of topological magnons via exchange interaction symmetry

## Abstract

Topological phases in magnetic materials offer novel tunability of topological properties via varying the underlying magnetism. We show that three dimensional Kitaev materials can provide a great opportunity for controlling symmetry-protected topological nodal magnons. These materials are originally considered as strong candidates for the Kitaev quantum spin liquid due to the bond-dependent frustrating spin exchange interactions. As a concrete example, we consider the symmetry and topology of the magnons in the canted zig-zag ordered state in the hyperhoneycomb $\beta\text{-}\mathrm{Li_2IrO_3}$, which can be obtained by applying a magnetic field in the counter-rotating spiral state at zero field. It is shown that the magnetic glide symmetries and the non-Hermitian nature of the bosonic magnons lead to unique topological protection that is different from the case of the fermionic counterparts. We investigate how such topological magnons can be controlled by changing the symmetry of the underlying spin exchange interactions.