Weyl Magnons in a Non-Coplanar Antiferromagnet

Building on our recently developed topological magnon materials catalog [1], we explore the first clear realization of the magnonic analog of Weyl electrons in the non-coplanar antiferromagnet MnTe₂. Using a combination of band representation analysis, inelastic neutron scattering (INS), magneto-Raman spectroscopy measurements, and linear spin wave theory, we determine that the non-coplanar nature of the antiferromagnetic ordering protects topological magnon nodal lines that breaks into Weyl magnons upon the application of specific symmetry-breaking perturbations. Zero-field INS measurements confirm the existence of the topological magnon nodal lines through the pseudo-spin winding of the scattering intensity in angular scans near the nodal lines, indicating the non-trivial topology of the magnon wavefunctions. Additionally, the emergence of Weyl magnons produces a direct signature on the bulk thermal Hall transport which we prove experimentally to agree with our theoretical predictions. Realizing and controlling Weyl magnons [2], this work allows further exploration of tunable topological behavior in bosonic systems, and highlights the rich interplay between magnetic order and band topology.

[1] Karaki, M.J., Fahmy, A.E., et al. High-throughput discovery of perturbation-induced topological magnons. npj Comput Mater 11, 216 (2025).

[2] Fahmy A.E., et al. Topological nodal Line and Weyl Magnons in the non-coplanar antiferromagnet MnTe₂. in preparation.