A unique van Hove singularity in kagome superconductor CsV${}_{3-x}$Ta${}_x$Sb${}_5$ with enhanced superconductivity

Abstract

Van Hove singularity (VHS) has been considered as a driving source for unconventional superconductivity. A VHS in two-dimensional (2D) materials consists of a saddle point connecting electron-like and hole-like bands. In a rare case, when a VHS appears at Fermi level, both electron-like and hole-like conduction can coexist, giving rise to an enhanced density of states as well as an attractive component of Coulomb interaction for unconventional electronic pairing. However, this van Hove scenario is often destroyed by an incorrect chemical potential or competing instabilities. Here, by using angle-resolved photoemission measurements, we report the observation of a VHS perfectly aligned with the Fermi level in a kagome superconductor CsV${}_{3-x}$Ta${}_x$Sb${}_5$ (x~0.4), in which a record-high superconducting transition temperature is achieved among all the current variants of AV${}_3$Sb${}_5$ (A=Cs, Rb, K) at ambient pressure. Doping dependent measurements reveal the important role of van Hove scenario in boosting superconductivity, and spectroscopic-imaging scanning tunneling microscopy measurements indicate a distinct superconducting state in this system.

20 pages, 4 figures

References in corpus (38)

• CsV${}_3$Sb${}_5$: a ${\mathbb{Z}}_2$ topological kagome metal with a superconducting ground state
• Discovery of unconventional chiral charge order in kagome superconductor KV3Sb5
• 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
• Charge density waves and electronic properties of superconducting kagome metals
• 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
• Three-dimensional charge density wave and robust zero-bias conductance peak inside the superconducting vortex core of a kagome superconductor CsV${}_3$Sb${}_5$
• Superconductivity and normal-state properties of kagome metal RbV3Sb5 single crystals
• Unusual competition of superconductivity and charge-density-wave state in a compressed topological kagome metal
• Observation of Unconventional Charge Density Wave without Acoustic Phonon Anomaly in Kagome Superconductors AV3Sb5 (A=Rb,Cs)
• Analysis of Charge Order in the Kagome Metal $A$V${}_3$Sb${}_5$ ($A=$K,Rb,Cs)
• Electronic instabilities of kagome metals: saddle points and Landau theory
• Nature of unconventional pairing in the kagome superconductors AV${}_3$Sb${}_5$
• Electronic Nature of Charge Density Wave and Electron-Phonon Coupling in Kagome Superconductor KV${}_3$Sb${}_5$
• 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 ${\text{AV}}_3{\text{Sb}}_5$
• Doped Kagome System as Exotic Superconductor
• Origin of the Charge Density Wave in the Kagome Metal CsV${}_3$Sb${}_5$ as Revealed by Optical Spectroscopy
• Multiple Energy Scales and Anisotropic Energy Gap in the Charge-Density-Wave Phase of Kagome Superconductor CsV3Sb5
• Emergence of new van Hove singularities in the charge density wave state of a topological kagome metal RbV3Sb5
• Charge-order-assisted topological surface states and flat bands in the kagome superconductor CsV${}_3$Sb${}_5$
• Fermi level tuning and double-dome superconductivity in the kagome metals CsV${}_3$Sb${}_{5-x}$Sn${}_x$
• Charge-density-wave-induced bands renormalization and energy gaps in a kagome superconductor RbV3Sb5
• Competition of superconductivity and charge density wave in selective oxidized CsV3Sb5 thin flakes
• Electron-phonon coupling in the charge density wave state of CsV${}_3$Sb${}_5$
• Optical detection of charge-density-wave instability in the non-magnetic kagome metal KV${}_3$Sb${}_5$
• Charge-Density-Wave-Induced Peak-Dip-Hump Structure and the Multiband Superconductivity in a Kagome Superconductor CsV${}_3$Sb${}_5$
• Evidence of a hidden flux phase in the topological kagome metal CsV${}_3$Sb${}_5$
• Competing superconductivity and charge-density wave in Kagome metal CsV3Sb5: evidence from their evolutions with sample thickness
• Distinctive momentum dependent charge-density-wave gap observed in CsV${}_3$Sb${}_5$ superconductor with topological Kagome lattice
• Optical study of RbV${}_3$Sb${}_5$: Multiple density-wave gaps and phonon anomalies
• Structural instability and charge modulations in the Kagome superconductor $A$V${}_3$Sb${}_5$
• Distinct band reconstructions in kagome superconductor CsV${}_3$Sb${}_5$
• Doping evolution of superconductivity, charge order and band topology in hole-doped topological kagome superconductors Cs(V${}_{1-x}$Ti${}_x$)${}_3$Sb${}_5$
• Titanium doped kagome superconductor CsV3-xTixSb5 and two distinct phases

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• Full-bandwidth anisotropic Migdal-Eliashberg theory and its application to superhydrides
• Evidence chain for time-reversal symmetry-breaking kagome superconductivity
• Electronic Landscape of Kagome Superconductors $\text{A}$V${}_3$Sb${}_5$ ($\text{A}$ = K, Rb, Cs) from Angle-Resolved Photoemission Spectroscopy
• Coexistence of near-EF flat band and van Hove singularity in a two-phase superconductor
• Kagome metals
• Evidence of a distinct collective mode in Kagome superconductors
• Self-consistent theory of $2\times 2$ pair density waves in kagome superconductors
• Origin of anomalous magnetotransport in kagome superconductors AV${}_3$Sb${}_5$ (A=K,Rb,Cs)
• Tunable vortex bound states in multiband CsV3Sb5-derived kagome superconductors
• Revealing the orbital origins of exotic electronic states with Ti substitution in kagome superconductor CsV3Sb5
• Two-dimensional phase diagram of the charge density wave in doped CsV${}_3$Sb${}_5$
• Superconductivity and a van Hove singularity confined to the surface of a topological semimetal
• Flat bands and distinct density wave orders in correlated Kagome superconductor CsCr${}_3$Sb${}_5$
• The de Haas-van Alphen quantum oscillations in the kagome metal RbTi3Bi5
• Local pairing versus bulk superconductivity intertwined by the charge density wave order in Cs(V${}_{1-x}$Ta${}_x$)${}_3$Sb${}_5$
• Inversion and Tunability of Van Hove Singularities in $A$V${}_3$Sb${}_5$ ($A$ = K, Rb, and Cs) kagome metals
• Moiré superlattices of antimonene on a Bi(111) substrate with van Hove singularity and Rashba-type spin polarization
• Strongly Entangled Kondo and Kagome Lattices and the Emergent Magnetic Ground State in Heavy-Fermion Kagome Metal YbV${}_6$Sn${}_6$
• Evidence of Mott Insulator with Thermally Induced Melting Behavior in Kagome Compound Nb3Cl8
• Designing Topological High-Order Van Hove Singularities: Twisted Bilayer Kagomé
• Low-dimensionality-induced tunable ferromagnetism in SrRuO${}_3$ ultrathin films
• Engineering magnetic anisotropy and ferromagnetism in topological Kagome metal GdV6Sn6 via Nd substitution
• Enhanced Coupling of Superconductivity and Evolution of Gap Structure in CsV3Sb5 through Ta Doping
• Effect of superconductivity by Nb and V substitution in kagome CaPd5