Abstract
In the quest for topology- and correlation-driven quantum states, kagome lattice materials have garnered significant interest for their band structures, featuring flat bands (FBs) from the quantum destructive interference of the electronic wavefunction. Tuning an FB to the chemical potential could induce electronic instabilities and emergent orders. Despite extensive studies, direct evidence of FBs tuned to the chemical potential and their role in emergent orders in bulk materials remains lacking. Using angle-resolved photoemission spectroscopy, resonant inelastic X-ray scattering, and density functional theory, we show that the low-energy structure of the Cr-based kagome metal superconductor CsCr3Sb5 is dominated by FBs at the Fermi level. We also observe low-energy magnetic excitations evolving across the low-temperature transition, largely consistent with the FB shift. Our results suggest that the low-temperature order contains a magnetic origin and that the kagome FBs may play a role in the emergence of this order.
| Original language | English |
|---|---|
| Article number | 7573 |
| Journal | Nature Communications |
| Volume | 16 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2025 |
Funding
The single-crystal synthesis work and RIXS experiments at Rice were supported by the U.S. DOE, BES under Grant No. DE-SC0012311 (P.D.). Part of the materials characterization efforts at Rice is supported by the Robert A. Welch Foundation Grant No. C-1839 (P.D.). The ARPES work at Rice University was supported by the U.S. DOE grant No. DE-SC0021421, the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant No. GBMF9470 and the Robert A. Welch Foundation Grant No. C-2175 (M.Y.). Y.G. is supported in part by an ALS Doctoral Fellowship in Residence. Y.Z. is partially supported by the Air Force Office of Scientific Research (AFOSR) Grant No. FA9550-21-1-0343. The RIXS work in Taiwan is partially supported by the National Science and Technology Council of Taiwan under Grant No. NSTC 112-2112-M-213-026-MY3 (D.J.H.) The theory work at Rice is supported by the NSF Grant No. DMR-2220603 (F.X. and Y.F.), by the AFOSR Grant No. FA9550-21-1-0356 (Y.W.), and by the Robert A. Welch Foundation Grant No. C-1411 (Q.S.), and by the Vannevar Bush Faculty Fellowship, ONR-VB N00014-23-1-2870 (Q.S.). Computational modeling was supported by the Office of Naval Research Grant N00014-22-1-2753 (Y.H. and B.I.Y.). The transport and thermodynamic measurements at UW were supported by the Air Force Office of Scientific Research (AFOSR) under Award No. FA2386-21-1-4060 and the David Lucile Packard Foundation (J.H.C). Work at the University of California, Berkeley and Lawrence Berkeley National Laboratory was funded by the U.S. DOE, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC02-05CH11231 (Quantum Materials Program KC2202). J.S.O., R.J.B., and M.Y. acknowledge the support from National Science Foundation (NSF) grants Nos. DMR-1921798 and DMR-2324032. M.H. and D.L. acknowledge the support of the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under contract DE-AC02-76SF00515. A.F. acknowledges the support of the National Science and Technology Council of Taiwan under Grant No. 113-2112-M-007-033, the Japan Society for the Promotion of Science under Grant No. JP22K03535, and the Yushan Fellow Program of the Ministry of Education of Taiwan. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by Oak Ridge National Laboratory.