Topological surface states and flat bands in the kagome superconductor CsV3Sb5

Hu, Yong; Teicher, Samuel M. L.; Ortiz, Brenden R.; Luo, Yang; Peng, Shuting; Huai, Linwei; Ma, Junzhang; Plumb, N. C.; Wilson, Stephen D.; He, Junfeng; Shi, M.

doi:10.1016/j.scib.2021.11.026

Cited by 84 publications

(55 citation statements)

References 41 publications

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“…2a, the DFT band calculation for CsV3Sb5 reveals four bands near EF: an electron-pocket at the Brillouin zone center G (G-band), dxy/dx2-y2 orbital kagome bands with Dirac point at » -0.27 eV and vHS near EF (K1-band), dxz/dyz orbital kagome bands with Dirac point at » -1.08 eV and vHS near EF (K2-band), and additional dxz/dyz orbital kagome bands with opposite parity from the K2-band (K2'-band). All band dispersions have been closely reproduced in previous ARPES studies 19,20,[36][37][38] . Meanwhile, we note that in the experimental geometry used in the present study, only G-, K1-, and K2-bands are visible in the ARPES spectra (see Fig.…”

supporting

confidence: 80%

Microscopic structure of three-dimensional charge order in kagome superconductor AV3Sb5 and its tunability

Kang

Fang

Yoo

et al. 2022

Preprint

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Correlated electronic systems are naturally susceptible to develop collective, symmetry-breaking electronic phases as observed in Cu- and Fe-based high-temperature superconductors, and twisted Moiré superlattices. The family of kagome metals AV3Sb5 (A = K, Rb, Cs) is a recently discovered, rich platform to study many of these phenomena and their interplay. In these systems, three-dimensional charge order (3D-CO) is the primary instability that sets the stage in which other ordered phases emerge, including unidirectional stripe order, orbital flux order, and superconductivity. Therefore, determining the exact nature of the 3D-CO is key to capture the broader phenomenology in AV3Sb5. Here, we use high-resolution angle-resolved photoemission spectroscopy to resolve the microscopic structure and symmetry of 3D-CO in AV3Sb5. Our approach is based on identifying an unusual splitting of kagome bands induced by 3D-CO, which provides a sensitive way to refine the spatial charge patterns in neighboring kagome planes. Notably, we found a marked dependence of the 3D-CO structure on alkali metal and doping: the 3D-CO in CsV3Sb5 is composed of kagome layers with alternating Star-of-David and Tri-Hexagonal distortions, while KV3Sb5, RbV3Sb5, and Sn-doped CsV3Sb5 realize a staggered charge pattern breaking C6 rotational symmetry. These results establish the microscopic structure of 3D-CO and its evolution with chemical composition for the first time, providing fresh insights on the origin of the cascade of exotic electronic phases in AV3Sb5.

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confidence: 80%

Microscopic structure of three-dimensional charge order in kagome superconductor AV3Sb5 and its tunability

Kang

Fang

Yoo

et al. 2022

Preprint

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“…There is also no magnetic resonance peak, which normally appears in superconductors with strong electron-electron correlation , such as cuprates and iron-based superconductors [25]. The weak electron-electron correlation in these materials is consistent with angle-resolved photoemission spectroscopy (ARPES) measurements [2,[26][27][28][29][30][31][32] and the first-principle calculations [33,34]. In addition, the SC is very sensitive to magnetic impurities but without any resonance peaks to non-magnetic impurities [35].…”

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confidence: 58%

Gapless excitations inside the fully gapped kagome superconductors AV$_3$Sb$_5$

Gu,

Zhang,

Feng

et al. 2021

Preprint

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The superconducting gap structures in the transition-metal-based kagome metal AV 3 Sb 5 (A=K,Rb,Cs), the first family of quasi-two-dimensional kagome superconductors, remain elusive as there is strong experimental evidence for both nodal and nodaless gap structures. Here we show that the dichotomy can be resolved because of the coexistence of time-reversal symmetry breaking with a conventional fully gapped superconductivity. The symmetry protects the edge states which arise on the domains of the lattice symmetry breaking order to remain gapless in proximity to a conventional pairing. We demonstrate this result in a four-band tight-binding model using the V d X 2 −Y 2 -like and the in-plane Sb p z -like Wannier functions that can faithfully capture the main feature of the materials near the Fermi level.

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“…Their emergence originates from the inherent features of the kagome lattice: substantial geometric spin frustration, flat bands, Dirac cones, and van Hove singularities (VHSs) at different electron fillings. Recently, a new family of kagome metal AV 3 Sb 5 (A = K, Rb, Cs) 26 with V kagome nets, was found to feature a ℤ 2 topological band structure 27 , 28 and superconductivity was realized with a maximum T c of 2.5 K at ambient pressure 27 . Moreover, they exhibit CDW order below T CDW ≈ 78–103 K 29 – 31 .…”

Section: Introductionmentioning

confidence: 99%

Rich nature of Van Hove singularities in Kagome superconductor CsV3Sb5

Ortiz

et al. 2022

Nat Commun

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121

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The recently discovered layered kagome metals AV3Sb5 (A = K, Rb, Cs) exhibit diverse correlated phenomena, which are intertwined with a topological electronic structure with multiple van Hove singularities (VHSs) in the vicinity of the Fermi level. As the VHSs with their large density of states enhance correlation effects, it is of crucial importance to determine their nature and properties. Here, we combine polarization-dependent angle-resolved photoemission spectroscopy with density functional theory to directly reveal the sublattice properties of 3d-orbital VHSs in CsV3Sb5. Four VHSs are identified around the M point and three of them are close to the Fermi level, with two having sublattice-pure and one sublattice-mixed nature. Remarkably, the VHS just below the Fermi level displays an extremely flat dispersion along MK, establishing the experimental discovery of higher-order VHS. The characteristic intensity modulation of Dirac cones around K further demonstrates the sublattice interference embedded in the kagome Fermiology. The crucial insights into the electronic structure, revealed by our work, provide a solid starting point for the understanding of the intriguing correlation phenomena in the kagome metals AV3Sb5.

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Topological surface states and flat bands in the kagome superconductor CsV3Sb5

Cited by 84 publications

References 41 publications

Microscopic structure of three-dimensional charge order in kagome superconductor AV3Sb5 and its tunability

Microscopic structure of three-dimensional charge order in kagome superconductor AV3Sb5 and its tunability

Gapless excitations inside the fully gapped kagome superconductors AV$_3$Sb$_5$

Rich nature of Van Hove singularities in Kagome superconductor CsV3Sb5

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