Spin waves and orbital contribution to ferromagnetism in a topological metal
Honeycomb and kagome lattices can host propagating excitations with non-trivial topology as defined by their evolution along closed paths in momentum space. Excitations on such lattices can also be momentum-independent, and the associated flat bands are of interest due to strong interactions between heavy quasiparticles. Here, we report the discovery - using circularly polarized X-rays for the unambiguous isolation of magnetic signals - of a nearly flat spin-wave band and large (compared to elemental iron) orbital moment in the metallic ferromagnet Fe<sub>3</sub>Sn<sub>2</sub> with compact AB-stacked kagome bilayers. As a function of out-of-plane momentum, the nearly flat optical mode and the global rotation symmetry-restoring acoustic mode are out of phase, consistent with a bilayer exchange coupling that is larger than the already large in-plane couplings. The defining units of this topological metal are therefore triangular lattices of octahedral iron clusters rather than weakly coupled kagome planes. The spin waves are strongly damped when compared to elemental iron, opening the topic of topological boson-fermion interactions for deeper exploration within this material platform.
Authors
- Thorsten Schmitt (ORCID: https://orcid.org/0000-0002-5737-1094)
- K. Kummer (ORCID: https://orcid.org/0000-0003-3044-7957)
- Vladimir N. Strocov (ORCID: https://orcid.org/0000-0002-1147-8486)
- Gabriel Aeppli
- Yi Tseng (ORCID: https://orcid.org/0000-0001-6788-4398)
- C. W. Galdino (ORCID: https://orcid.org/0000-0002-4786-344X)
- Yeong‐Ah Soh
- Tianlun Yu (ORCID: https://orcid.org/0000-0001-8973-2782)
- Yimin Xiong (ORCID: https://orcid.org/0000-0003-2736-8334)
- Zhijia Zhang (ORCID: https://orcid.org/0000-0002-3903-1184)
- Teguh Citra Asmara (ORCID: https://orcid.org/0000-0002-1359-734X)
- Wenliang Zhang (ORCID: https://orcid.org/0000-0003-3278-4076)
- Junbo Li (ORCID: https://orcid.org/0000-0002-6329-6043)
- Wei Yuan (ORCID: https://orcid.org/0009-0001-3427-6764)
Institutions
- Anhui University (CN)
- Chinese Academy of Sciences (CN)
- European Synchrotron Radiation Facility (FR)
- Paul Scherrer Institute (CH)
- Hefei Institutes of Physical Science (CN)
- ETH Zurich (CH)
- Hefei University (CN)
- High Magnetic Field Laboratory (CN)
- École Polytechnique Fédérale de Lausanne (CH)
- European X-Ray Free-Electron Laser (DE)
- University of Lausanne (CH)
Publication Details
- Journal
- Nature Communications
- Published
- 2024-10-16
- DOI
- https://doi.org/10.1038/s41467-024-53152-1
- Citations
- 7
- Primary Topic
- Advanced Condensed Matter Physics
- Type
- article
- Field-Weighted Citation Impact
- 2.18
Funders
- National Science Foundation
- European Commission
- European Synchrotron Radiation Facility
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
- Paul Scherrer Institut