Abstract
Exploring the relationship between intriguing physical properties and structural complexity is a central topic in studying modern functional materials. Co3Sn2S2, a newly discovered kagome-lattice magnetic Weyl semimetal, has triggered intense interest owing to the intimate coupling between topological semimetallic states and peculiar magnetic properties. However, the origins of the magnetic phase separation and spin glass state below TC in this ordered compound are two unresolved yet important puzzles in understanding its magnetism. Here, we report the discovery of local symmetry breaking surprisingly co-emerges with the onset of ferromagnetic order in Co3Sn2S2, by a combined use of neutron total scattering and half-polarized neutron diffraction. An anisotropic distortion of the cobalt kagome lattice at the atomic/nano level is also found, with distinct distortion directions among the two Co1 and four Co2 atoms. The mismatch of local and average symmetries occurs below TC, indicating that Co3Sn2S2 evolves to an intrinsically lattice disordered system when the ferromagnetic order is established. The local symmetry breaking with intrinsic lattice disorder provides new understanding of the puzzling magnetic properties. Our density functional theory (DFT) calculation indicates that the local symmetry breaking is expected to reorient local ferromagnetic moments, unveiling the existence of the ferromagnetic instability associated with the lattice instability. Furthermore, DFT calculation unveils that the local symmetry breaking could affect the Weyl property by breaking the mirror plane. Our findings highlight the fundamentally important role that the local symmetry breaking plays in advancing our understanding on the magnetic and topological properties in Co3Sn2S2, which may draw attention to explore the overlooked local symmetry breaking in Co3Sn2S2, its derivatives and more broadly in other topological Dirac/Weyl semimetals and kagome-lattice magnets.
| Original language | English |
|---|---|
| Pages (from-to) | 14339-14350 |
| Number of pages | 12 |
| Journal | Journal of the American Chemical Society |
| Volume | 144 |
| Issue number | 31 |
| DOIs | |
| State | Published - Aug 10 2022 |
Funding
The neutron research used resources at High Flux Isotope Reactor and Spallation Neutron Source, DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory. The research by S.O., J.Y., M.A.M., and D.A.T. was sponsored by the Laboratory Directed Research and Development Program (LDRD) of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy (Project ID 9533), with the later stage supported by the U.S. DOE, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (J.Y.), and U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Quantum Science Center (S.O., M.A.M., D.A.T.). This research used resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725.
| Funders | Funder number |
|---|---|
| CADES | DE-AC05-00OR22725 |
| Data Environment for Science | |
| National Quantum Information Science Research Centers | |
| Quantum Science Center | |
| U.S. Department of Energy | 9533 |
| Office of Science | |
| Basic Energy Sciences | |
| Oak Ridge National Laboratory | |
| Laboratory Directed Research and Development | |
| Division of Materials Sciences and Engineering |