Chiral excitonic order from twofold van Hove singularities in kagome metals

Abstract

Recent experiments on kagome metals AV${}_3$Sb${}_5$ (A=K,Rb,Cs) [M. Kang et al., Nat. Phys. 18, 301-308 (2022)] identify twofold van Hove singularities (TvHS) with opposite concavity near the Fermi energy, generating two approximately hexagonal Fermi surfaces -- one electron-like and the other hole-like. Here we propose that a TvHS generates a novel time-reversal symmetry breaking excitonic order -- arising due to bound pairs of electrons and holes located at opposite concavity van Hove singularities. We introduce a minimal model for the TvHS and investigate interaction induced many-body instabilities via the perturbative renormalisation group technique and a free energy analysis. Specialising to parameters appropriate for the kagome metals AV${}_3$Sb${}_5$, we construct a phase diagram comprising chiral excitons, charge density wave and a region of coexistence. We propose this as an explanation of a diverse range of experimental observations in AV${}_3$Sb${}_5$. Notably, the chiral excitonic state gives rise to a quantum anomalous Hall conductance, providing an appealing interpretation of the observed anomalous Hall effect in kagome metals. Possible alternative realisations of the TvHS mechanism in bilayer materials are also discussed. We suggest that TvHS open up interesting possibilities for correlated phases, enriching the set of competing ground states to include excitonic order.

References in corpus (55)

• High temperature fractional quantum Hall states
• CsV${}_3$Sb${}_5$: a ${\mathbb{Z}}_2$ topological kagome metal with a superconducting ground state
• Nearly-flat bands with nontrivial topology
• Discovery of unconventional chiral charge order in kagome superconductor KV3Sb5
• Chiral superconductivity from repulsive interactions in doped graphene
• Roton pair density wave and unconventional strong-coupling superconductivity in a topological kagome metal
• Cascade of correlated electron states in a kagome superconductor CsV3Sb5
• Unconventional Fermi surface instabilities in the Kagome Hubbard Model
• Time-reversal symmetry-breaking charge order in a kagome superconductor
• Superconductivity in the ${\mathbb{Z}}_2$ kagome metal KV${}_3$Sb${}_5$
• Double superconducting dome and triple enhancement of Tc in the kagome superconductor CsV3Sb5 under high pressure
• Superconductivity and normal-state properties of kagome metal RbV3Sb5 single crystals
• Bright excitons in monolayer transition metal dichalcogenides: from Dirac cones to Dirac saddle points
• Analysis of Charge Order in the Kagome Metal $A$V${}_3$Sb${}_5$ ($A=$K,Rb,Cs)
• Zero-field superconducting diode effect in small-twist-angle trilayer graphene
• Electronic instabilities of kagome metals: saddle points and Landau theory
• Correlation-driven chiral superconductivity and chiral spin order in doped kagome lattice
• Sublattice Interference in the Kagome Hubbard Model
• Nature of unconventional pairing in the kagome superconductors AV${}_3$Sb${}_5$
• Rotation symmetry breaking in the normal state of a kagome superconductor KV3Sb5
• Rich Nature of Van Hove Singularities in Kagome Superconductor CsV${}_3$Sb${}_5$
• Complex charge density waves at Van Hove singularity on hexagonal lattices: Haldane-model phase diagram and potential realization in kagome metals ${\text{AV}}_3{\text{Sb}}_5$
• Multiband superconductivity with sign-preserving order parameter in kagome superconductor CsV3Sb5
• Interaction-driven topological insulators on the kagome and the decorated honeycomb lattices
• Truncation of a 2-dimensional Fermi surface due to quasiparticle gap formation at the saddle points
• Pressure-induced Reemergence of Superconductivity in Topological Kagome Metal CsV3Sb5
• Intrinsic nature of chiral charge order in the kagome superconductor RbV3Sb5
• Interplay between charge order and superconductivity in the kagome metal KV${}_3$Sb${}_5$
• Nodeless superconductivity in the kagome metal CsV${}_3$Sb${}_5$
• Isolated Flat Bands and Spin-1 Conical Bands in Two-Dimensional Lattices
• Twisted Trilayer Graphene: a Precisely Tunable Platform for Correlated Electrons
• Absence of local moments in the kagome metal KV3Sb5 as determined by muon spin spectroscopy
• Anisotropic superconducting properties of Kagome metal CsV3Sb5
• Fermi level tuning and double-dome superconductivity in the kagome metals CsV${}_3$Sb${}_{5-x}$Sn${}_x$
• Strongly enhanced tunneling at total charge neutrality in double bilayer graphene-WSe${}_2$ heterostructures
• Theory of zero-field superconducting diode effect in twisted trilayer graphene
• Induced spin-orbit coupling in twisted graphene-TMDC heterobilayers: twistronics meets spintronics
• Valley Polarization and Inversion in Strained Graphene via Pseudo-Landau Levels, Valley Splitting of Real Landau Levels and Confined States
• Microscopic evidence for anisotropic multigap superconductivity in the CsV${}_3$Sb${}_5$ kagome superconductor
• Revealing the competition between charge-density wave and superconductivity in CsV${}_3$Sb${}_5$ through uniaxial strain
• Double-dome superconductivity under pressure in the V-based Kagome metals AV3Sb5 (A = Rb and K)
• A chiral twist on the high-$T_c$ phase diagram in Moiré heterostructures
• Geometry of the charge density wave in kagom$\acute{e}$ metal AV${}_3$Sb${}_5$
• Superconductivity from repulsive interaction
• Topologically protected excitons in porphyrin thin films
• Role of Sb in the superconducting kagome metal CsV${}_3$Sb${}_5$ revealed by its anisotropic compression
• Exciton Transport and Andreev Reflection in a Bilayer Quantum Hall System
• Electronic structure calculations of twisted multi-layer graphene superlattices
• Van Hove tuning of AV3Sb5 kagome metals under pressure and strain
• Resonant manifestations of chiral excitons in magnetooptical Faraday and Kerr effects in topological insulator film
• Evolution of superconductivity and charge order in pressurized RbV${}_3$Sb${}_5$
• Flat band topology of magic angle graphene on a transition metal dichalcogenide
• Current Switching of Valley Polarization in Twisted Bilayer Graphene
• Tunneling and Fluctuating Electron-Hole Cooper Pairs in Double Bilayer Graphene
• Chiral topological excitons in the monolayer transition metal dichalcogenides

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• Quantum states and intertwining phases in kagome materials
• Abundant lattice instability in kagome metal ScV${}_6$Sn${}_6$
• Charge-loop current order and Z3 nematicity mediated by bond-order fluctuations in kagome metal AV3Sb5 (A=Cs,Rb,K)
• Commensurate-to-incommensurate transition of charge-density-wave order and a possible quantum critical point in pressurized kagome metal CsV${}_3$Sb${}_5$
• Intertwined van-Hove Singularities as a Mechanism for Loop Current Order in Kagome Metals
• Novel three-dimensional Fermi surface and electron-correlation-induced charge density wave in FeGe
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• The discovery of three-dimensional Van Hove singularity
• Drastic magnetic-field-induced chiral current order and emergent current-bond-field interplay in kagome metals
• The kagome Hubbard model from a functional renormalization group perspective
• Van-Hove annihilation and nematic instability on a Kagome lattice
• Kagome metals
• Emergent topological quantum orbits in the charge density wave phase of kagome metal CsV${}_3$Sb${}_5$
• Enhanced nematicity emerging from higher-order van Hove singularities
• Existence of Hebel-Slichter peak in unconventional kagome superconductors
• Condensation of preformed charge density waves in kagome metals
• Origin of anomalous magnetotransport in kagome superconductors AV${}_3$Sb${}_5$ (A=K,Rb,Cs)
• Two elementary band representation model, Fermi surface nesting, and surface topological superconductivity in $A$V${}_3$Sb${}_5$ ($A=\text{K, Rb, Cs}$)
• Perspective: imaging atomic step geometry to determine surface terminations of kagome materials and beyond
• Unified picture of superconductivity and magnetism in CeRh${}_2$As${}_2$
• Interplay between Chiral Charge Density Wave and Superconductivity in Kagome Superconductors: A Self-consistent Theoretical Analysis
• Three-dimensional higher-order saddle points induced flat bands in Co-based kagome metals
• Real-space Loop Current Pattern in Time-reversal-symmetry Breaking Phase in Kagome Metals
• Higher-Order Van Hove Singularities in Kagome Topological Bands
• Quantum-metric-induced giant and reversible nonreciprocal transport phenomena in chiral loop-current phases of kagome metals
• Superconductivity and pair density waves from nearest-neighbor interactions in frustrated lattice geometries
• Low temperature phase transitions under CDW state in kagome metals AV3Sb5 (A=Cs,Rb,K): Significance of mix-type Fermi surface electron correlations
• Electronic structure of $A$V${}_3$Sb${}_5$ kagome metals
• MPd5 kagome superconductors studied by density functional calculations
• High-order van Hove singularities and nematic instability in the kagome superconductor CsTi${}_3$Bi${}_5$
• Common sublattice-pure van Hove singularities in the kagome superconductors $\text{A}$V${}_3$Sb${}_5$ ($\text{A}$ = K, Rb, Cs)
• Constraints on the orbital flux phase in $A$V${}_3$Sb${}_5$ from polar Kerr effect
• Vestigial $d$-wave charge-$4e$ Superconductivity from Bidirectional Pair Density Waves
• Superconductivity and Electron Correlations in Kagome Metal LuOs3B2
• Origin of switchable quasiparticle-interference chirality in loop-current phase of kagome metals measured by scanning-tunneling-microscopy
• Crystallization of the transdimensional electron liquid
• Odd-parity quadrupole order and induced nonreciprocal transport in the kagome metal CsTi${}_3$Bi${}_5$ driven by quantum interference
• Loop-current order through the kagome looking glass
• Recent progress in quantum spin liquids, fractional magnetization plateaus, and unconventional superconductivity in kagome lattices
• Orbital altermagnetism on the kagome lattice and possible application to $A$V${}_3$Sb${}_5$
• Giant Impurity Effects on Charge Loop Current Order States in Kagome Metals
• Magnetic-field effect on excitonic condensation emergent in extended Falicov-Kimball model
• Kekulé order from diffuse nesting near higher-order Van Hove points
• Magnetism of kagome metals $\left({\text{Fe}}_{1-x}{\text{Co}}_x\right)\text{Sn}$ studied by $\mu$SR
• Theory of unconventional magnetism in a Cu-based kagome metal
• Microscopic origin of period-four stripe charge-density-wave in kagome metal CsV${}_3$Sb${}_5$