Einstein-de Haas Effect of Topological Magnons

TL;DR

This paper predicts a measurable Einstein-de Haas effect in topological magnon insulators, showing a temperature-dependent sign change in angular momentum and proposing experimental setups and candidate materials for observation.

Contribution

It introduces the prediction of the Einstein-de Haas effect in topological magnon insulators and suggests specific lattice materials and experimental methods for detection.

Findings

Sign change in angular momentum with temperature in topological magnon states

Strongest effect observed in square-octagon lattice

Proposed experimental setup and candidate materials for testing

Abstract

We predict the existence of Einstein-de Haas effect in topological magnon insulators. Temperature variation of angular momentum in the topological state shows a sign change behavior, akin to the low temperature thermal Hall conductance response. This manifests itself as a macroscopic mechanical rotation of the material hosting topological magnons. We show that an experimentally observable Einstein-de Haas effect can be measured in the square-octagon, the kagome, and the honeycomb lattices. Albeit, the effect is the strongest in the square-octagon lattice. We treat both the low and the high temperature phases using spin wave and Schwinger boson theory, respectively. We propose an experimental set up to detect our theoretical predictions. We suggest candidate square-octagon materials where our theory can be tested.