Direct optical probe of magnon topology in two-dimensional quantum magnets

TL;DR

This paper introduces an optical method using two-magnon Raman circular dichroism to directly probe the topological properties of magnon bands in two-dimensional quantum magnets, facilitating experimental detection of magnon topology.

Contribution

It establishes a fundamental relation between light-matter coupling and magnon quantum geometry, enabling optical detection of magnon topology in honeycomb magnets.

Findings

Derived a relation linking light-matter interaction to magnon quantum geometry.

Proposed two-magnon Raman circular dichroism as an optical probe for magnon topology.

Facilitated experimental detection of Chern number and topological gap in magnon systems.

Abstract

Controlling edge states of topological magnon insulators is a promising route to stable spintronics devices. However, to experimentally ascertain the topology of magnon bands is a challenging task. Here we derive a fundamental relation between the light-matter coupling and the quantum geometry of magnon states. This allows to establish the two-magnon Raman circular dichroism as an optical probe of magnon topology in honeycomb magnets, in particular of the Chern number and the topological gap. Our results pave the way for interfacing light and topological magnons in functional quantum devices.