Tuning bulk topological magnon properties with light-induced magnons

Abstract

Although theoretical modeling and inelastic neutron scattering measurements have indicated the presence of topological magnon bands in multiple quantum magnets, experiments remain unable to detect a signal of the magnon thermal Hall effect in the quantum magnets, which is a consequence of magnons condensation at the bottom of the bands following Bose-Einstein statistics as well as the concentration of Berry curvature at the higher energies. In recent work, Malz et al. [Nat. Commun. 10, 3937 (2019)] have shown that topological magnons in edge states in a finite sample can be amplified using tailored electromagnetic fields. We extend their approach by showing that a uniform electromagnetic field can selectively amplify magnons with finite Berry curvature by breaking the inversion symmetry of a lattice. Using this approach, we demonstrate the generation of bulk topological magnons in a Heisenberg ferromagnet on the breathing kagome lattice and the consequent amplification of the thermal Hall effect.