Photo-induced Floquet Weyl magnons in noncollinear antiferromagnets

TL;DR

This paper demonstrates how off-resonant light can induce Weyl magnon nodes and thermal Hall effects in noncollinear antiferromagnets, enabling control over their topological magnetic properties.

Contribution

It introduces a mechanism for photoinducing Weyl magnons and thermal Hall effects in 3D antiferromagnets with noncollinear spin structures, expanding the possibilities for topological magnonics.

Findings

Photoinduced Weyl magnon nodes along the $k_x$ direction.

Observation of photoinduced magnon thermal Hall effect.

Chiral spin structures can be manipulated with light.

Abstract

We study periodically driven insulating noncollinear stacked kagome antiferromagnets with a conventional symmetry-protected three-dimensional (3D) in-plane $120^\circ$ spin structure, with either positive or negative vector chirality. We show that the symmetry protection of the in-plane $120^\circ$ spin structure can be broken in the presence of an off-resonant circularly or linearly polarized electric field propagating parallel to the in-plane $120^\circ$ spin structure (say along the $x$ direction). Consequently, topological Floquet Weyl magnon nodes with opposite chirality are photoinduced along the $k_x$ momentum direction. They manifest as the monopoles of the photoinduced Berry curvature. We also show that the system exhibits a photoinduced magnon thermal Hall effect for circularly polarized electric field. Furthermore, we show that the photoinduced chiral spin structure is a canted 3D in-plane $120^\circ$ spin structure, which was recently observed in the equilibrium noncollinear antiferromagnetic Weyl semimetals Mn$_3$Sn\slash Ge. Our result not only paves the way towards the experimental realization of Weyl magnons and photoinduced thermal Hall effects, but also provides a powerful mechanism for manipulating the intrinsic properties of 3D topological antiferromagnets.