Three-dimensional energy gap and origin of charge-density wave in kagome superconductor KV3Sb5

Abstract

Kagome lattices offer a fertile ground to explore exotic quantum phenomena associated with electron correlation and band topology. The recent discovery of superconductivity coexisting with charge-density wave (CDW) in the kagome metals KV3Sb5, RbV3Sb5, and CsV3Sb5 suggests an intriguing entanglement of electronic order and superconductivity. However, the microscopic origin of CDW, a key to understanding the superconducting mechanism and its possible topological nature, remains elusive. Here, we report angle-resolved photoemission spectroscopy of KV3Sb5 and demonstrate a substantial reconstruction of Fermi surface in the CDW state that accompanies the formation of small three-dimensional pockets. The CDW gap exhibits a periodicity of undistorted Brillouin zone along the out-of-plane wave vector, signifying a dominant role of the in-plane inter-saddle-point scattering to the mechanism of CDW. The characteristics of experimental band dispersion can be captured by first-principles calculations with the inverse star-of-David structural distortion. The present result indicates a direct link between the low-energy excitations and CDW, and puts constraints on the microscopic theory of superconductivity in alkali-metal kagome lattices.

25 pages, 3 figures

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• AV${}_3$Sb${}_5$ Kagome Superconductors: Progress and Future Directions
• Microscopic nature of the charge-density wave in kagome superconductor RbV${}_3$Sb${}_5$
• Fermiology and Origin of Tc Enhancement in a Kagome Superconductor Cs(V1-xNbx)3Sb5
• Intertwined van-Hove Singularities as a Mechanism for Loop Current Order in Kagome Metals
• Unconventional superconductivity protected from disorder on the kagome lattice
• Small Fermi pockets intertwined with charge stripes and pair density wave order in a kagome superconductor
• Magnetic Breakdown and Topology in the Kagome Superconductor CsV3Sb5 under High Magnetic Field
• Polarity-dependent charge-density wave in a kagome superconductor CsV3Sb5
• Surface-termination-dependent electronic states in kagome superconductors AV3Sb5 (A = K, Rb, Cs) studied by micro-ARPES
• Origin of $\pi$-shifted three-dimensional charge density waves in kagome metal AV${}_3$Sb${}_5$
• Diverse electronic landscape of the kagome metal YbTi3Bi4
• Low-Energy Electronic Structure in the Unconventional Charge-Ordered State of ScV${}_6$Sn${}_6$
• Origin of anomalous magnetotransport in kagome superconductors AV${}_3$Sb${}_5$ (A=K,Rb,Cs)
• Revealing Rotational Symmetry Breaking Charge-density Wave Order in Kagome Superconductor (Rb, K)V${}_3$Sb${}_5$ by Ultrafast Pump-probe Experiments
• Chiral pair density wave as a precursor of the pseudogap in kagomé superconductors
• Lattice dynamics study of electron-correlation-induced charge density wave in antiferromagnetic kagome metal FeGe
• Photoemission Insights to Electronic Orders in Kagome Superconductor AV3Sb5
• Impact of charge-density-wave pattern on the superconducting gap in V-based kagome superconductors
• Origin of switchable quasiparticle-interference chirality in loop-current phase of kagome metals measured by scanning-tunneling-microscopy
• Electronic inhomogeneity in Cs- and Sb-terminated surfaces of CsV${}_3$Sb${}_5$ probed by scanning photoemission spectromicroscopy
• Giant Impurity Effects on Charge Loop Current Order States in Kagome Metals
• Role of On-site and Inter-site Coulomb Interactions in KV${}_3$Sb${}_5$: A first-principles DFT+$U$+$V$ study