Twofold van Hove singularity and origin of charge order in topological kagome superconductor CsV3Sb5

Mingu Kang, Shiang Fang, Jeong Kyu Kim, Brenden R. Ortiz, Sae Hee Ryu, Jimin Kim, Jonggyu Yoo, Giorgio Sangiovanni, Domenico Di Sante, Byeong Gyu Park, Chris Jozwiak, Aaron Bostwick, Eli Rotenberg, Efthimios Kaxiras, Stephen D. Wilson, Jae Hoon Park, Riccardo Comin

Research output: Contribution to journalArticlepeer-review

244 Scopus citations

Abstract

The layered vanadium antimonides AV3Sb5 (A = K, Rb, Cs) are a recently discovered family of topological kagome metals that exhibit a range of strongly correlated electronic phases including charge order and superconductivity. However, it is not yet understood how the distinctive electronic structure of the kagome lattice is linked to the observed many-body phenomena. Here we combine angle-resolved photoemission spectroscopy and density functional theory to reveal multiple kagome-derived van Hove singularities (vHS) coexisting near the Fermi level of CsV3Sb5 and analyse their contribution to electronic symmetry breaking. The vHS are characterized by two distinct sublattice flavours (p-type and m-type), which originate, respectively, from their pure and mixed sublattice characters. These twofold vHS flavours of the kagome lattice critically determine the pairing symmetry and unconventional ground states emerging in the AV3Sb5 series. We establish that, among the multiple vHS in CsV3Sb5, the m-type vHS of the dxz/dyz kagome band and the p-type vHS of the dxy/dx2–y2 kagome band are located very close to the Fermi level, setting the stage for electronic symmetry breaking. The former band is characterized by pronounced Fermi surface nesting, while the latter exhibits a higher-order vHS. Our work reveals the essential role of kagome-derived vHS for the collective phenomena realized in the AV3Sb5 family.

Original languageEnglish
Pages (from-to)301-308
Number of pages8
JournalNature Physics
Volume18
Issue number3
DOIs
StatePublished - Mar 2022
Externally publishedYes

Funding

We thank S. Jung for fruitful discussions. This work was supported by the Air Force Office of Scientific Research Young Investigator Program under grant FA9550-19-1-0063, and by the STC Center for Integrated Quantum Materials (NSF grant no. DMR-1231319). Work at Max Planck POSTECH Korea Research Initiative was supported by the National Research Foundation of Korea, Ministry of Science (grant no. 2016K1A4A4A01922028). B.R.O. and S.D.W. were supported by the National Science Foundation (NSF) through Enabling Quantum Leap: Convergent Accelerated Discovery Foundries for Quantum Materials Science, Engineering and Information (Q-AMASE-i): Quantum Foundry at UC Santa Barbara (DMR-1906325). This research used resources of the Advanced Light Source, a US DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. M.K. acknowledges a Samsung Scholarship from the Samsung Foundation of Culture. S.F. acknowledges support from a Rutgers Center for Material Theory Distinguished Postdoctoral Fellowship. B.R.O. acknowledges support from the California NanoSystems Institute through the Elings Fellowship programme. The research leading to these results has received funding from the European Union Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement no. 897276. G.S. is grateful for funding support from the Deutsche Forschungsgemeinschaft (DFG) under Germany’s Excellence Strategy through the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter ct.qmat (EXC 2147, project ID 390858490) as well as through the Collaborative Research Center SFB 1170 ToCoTronics (project ID 258499086).

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