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

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

doi:10.1038/s41567-021-01451-5

Cited by 258 publications

(166 citation statements)

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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 » -1.3 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: 82%

“…Notably, previous theoretical and experimental investigations point toward the unique role of the electronic structure of the underlying kagome lattice in driving the rich physics of AV3Sb5 [14][15][16][17][18][19][20] . In the ideal limit, the kagome lattice exhibits multiple singularities in its electronic dispersion, including Dirac fermions at the Brillouin zone corner K, van Hove singularity (vHS) at the zone edge M, and flat bands across the whole Brillouin zone (Fig.…”

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confidence: 99%

“…Combined with the high density of states at vHS, the nesting creates a diverging electronic susceptibility and sets the stage for pairing in multiple channels, and the subsequent emergence of charge/spin order and superconductivity [24][25][26] . The electronic structure of the AV3Sb5 series follows this script, with multiple kagome-derived vHS sharply aligned to the Fermi level (EF) [16][17][18][19][20] . Accordingly, as displayed in Fig.…”

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

Kang

Fang

Yoo

et al. 2022

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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: 99%

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

Kang

Fang

Yoo

et al. 2022

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“…2d) consist of a mixed contribution from both the B and C sublattices (Supplementary Fig. 3), referred to as a mixed-type flavor [12,20,40]. This is in contrast to the type-I VHS point at Γ (Fig.…”

Section: Rearrangement Of Vhssmentioning

confidence: 96%

Monolayer Kagome Metals AV3Sb5

Kim¹,

Oh²,

Moon³

et al. 2022

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Recently, layered kagome metals AV 3 Sb 5 (A = K, Rb, and Cs) have emerged as a fertile platform for exploring frustrated geometry, correlations, and topology. Here we demonstrate that AV 3 Sb 5 can crystallize in a mono-layered form, revealing a range of properties that render the system unique by using first-principles and mean-field calculations. Most importantly, the two-dimensional monolayer preserves intrinsically different symmetries from the three-dimensional layered bulk, enforced by stoichiometry. Enrichment of the van Hove singularities, a logarithmic divergence of electronic density of states, consequently appears, leading to a variety of competing instabilities such as doublets of charge density waves and s-and d-wave superconductivity. We show that the competition between orders can be fine-tuned in the monolayer via electron-filling of the van Hove singularities. Thus, our results suggest the monolayer kagome metal AV 3 Sb 5 as a promising platform for designer metallic quantum phases. The kagome lattice refers to a two-dimensional (2D) planar crystal composed of corner-sharing triangles. Unique electronic structures emerge owing to the geometrical frustration of the lattice, featuring a flat band, a pair of Dirac points, and saddle-point van Hove singularities (VHSs). A prominent example of candidate kagome metals is the recently discovered vanadium-based kagome metals AV 3 Sb 5 (A = K, Rb, and Cs) [1, 2]. A cascade of correlated electronic states have been observed in AV 3 Sb 5 , associated with charge density waves (CDWs) [2-17] and superconductivity [2, 14-23]. These phases are reported to be accompanied by concomitant unexpected properties such as giant anomalous Hall effects [24, 25] without long-ranged magnetic ordering [26], potential Majorana zero modes [14], and edge supercurrent [18]. The VHSs in conjugation with the Coulomb interaction is suggested as an impetus of the unconventional properties [27, 28].Although many outstanding materials have been found to comprise a kagome lattice in a layered form [29][30][31], the kagome lattice in genuine two dimensions is rare in nature. This scarcity leads to prior explorations of the kagome materials based on the assumption that a three-dimensional (3D) layered system can be regarded as decoupled kagome layers. Similarly, in the case of the vanadium-

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“…It deserves to remark on the charge density gaps which are about 2∆ ≈ 40 meV determined by STM [20], ARPES [35,60,61], and ultrafast measurements [38]. The CDW gap opening signatures, namely the suppression of the low-energy spectra weight and the enhancement of the spectra weight close to 2∆ ≈ 40 meV, are not observed in the Raman response both in the A 1g and E 2g channels.…”

Section: Phonon Modesmentioning

confidence: 95%

Charge density wave order in kagome metal AV$_3$Sb$_5$ (A= Cs, Rb, K)

Wu,

Ortiz,

Tan

et al. 2022

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We employ polarization-resolved electronic Raman spectroscopy and density functional theory to study the primary and secondary order parameters, as well as their interplay, in the charge density wave (CDW) state of the kagome metal AV3Sb5. Previous x-ray diffraction data at 15 K established that the CDW order in CsV3Sb5 comprises of a 2 × 2 × 4 structure: one layer of inverse-starof-David and three consecutive layers of star-of-David pattern. We analyze the lattice distortions based the 2 × 2 × 4 structure at 15 K, and find that U1 lattice distortion is the primary-like (leading) order parameter while M + 1 and L − 2 distortions are secondary-like order parameters for Vanadium displacements. This conclusion is confirmed by the calculation of bare susceptibility χ 0 (q) that shows a broad peak at around qz = 0.25 along the hexagonal Brillouin zone face central line (Uline). We also identify several phonon modes emerging in the CDW state, which are lattice vibration modes related to V and Sb atoms as well as alkali atoms. The detailed temperature evolution of these modes' frequencies, half-width-at-half-maximums, and integrated intensities support a phase diagram with two successive structural phase transitions in CsV3Sb5: the first one with a primarylike order parameter appearing at TS = 94 K and the second isostructural one appearing at around T * = 70 K. Furthermore, the T -dependence of the integrated intensity for these modes show two types of behavior below TS: the low-energy modes show a plateau-like behavior below T * while the high-energy modes monotonically increase below TS. These two behaviors are captured by Landau free energy model incorporating the interplay between the primary-like and the secondarylike order parameters via trilinear coupling. Especially, the sign of the trilinear term that couples order parameters with different wave-vectors determines whether the primary-like and secondarylike order parameters cooperate or compete with each other, thus determining the shape of the T -dependence of the intensities of Bragg peak in x-ray data and the amplitude modes in Raman data below TS. These results provide an accurate basis for studying the interplay between multiple CDW order parameters in kagome metal systems. I. INTRODUCTIONKagome lattice is a model system to study the electronic and magnetic properties [1,2]. The corner shared triangle network of the kagome lattice enables three sublattice interference, which give rise to a variety of exotic physics, for example, flat bands, van Hove singularities, Dirac-dispersions in its electronic structure, frustrated magnetism, to name a few. Various electronic orders such as charge/spin density wave order, charge bond order, chiral flux order, nematic order, and superconductivity are under rigorous investigations [3][4][5][6][7][8][9][10][11][12][13][14][15][16].Recently, a three-dimensional charge density wave (CDW) order, which coexists with superconductivity (SC) at low temperatures, was discovered in AV 3 Sb 5 (A= Cs, Rb, K) kagome metals [Fig. 1 ...

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

Cited by 258 publications

References 49 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

Monolayer Kagome Metals AV3Sb5

Charge density wave order in kagome metal AV$_3$Sb$_5$ (A= Cs, Rb, K)

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