Abstract
The kagome lattice is a fertile platform to explore topological excitations with both Fermi-Dirac and Bose-Einstein statistics. While relativistic Dirac fermions and flat bands have been discovered in the electronic structure of kagome metals, the spin excitations have received less attention. Here, we report inelastic neutron scattering studies of the prototypical kagome magnetic metal FeSn. The spectra display well-defined spin waves extending to 120 meV. Above this energy, the spin waves become progressively broadened, reflecting interactions with the Stoner continuum. Using linear spin-wave theory, we determine an effective spin Hamiltonian that reproduces the measured dispersion. This analysis indicates that the Dirac magnon at the K point remarkably occurs on the brink of a region where well-defined spin waves become unobservable. Our results emphasize the influential role of itinerant carriers on the topological spin excitations of metallic kagome magnets.
| Original language | English |
|---|---|
| Article number | L180403 |
| Journal | Physical Review B |
| Volume | 105 |
| Issue number | 18 |
| DOIs | |
| State | Published - May 1 2022 |
Funding
Acknowledgments. We acknowledge M. Lumsden and J. M. Ok for useful discussions. This research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division. Work at the Oak Ridge National Laboratory Spallation Neutron Source was supported by U.S. DOE, Office of Science, BES, Scientific User Facilities Division. The neutron experiment at the Materials and Life Science Experimental Facility of the J-PARC was performed under a user program (Proposals No. 2019B0248 and No. 2020A0217).