Phonon collapse and anharmonic melting of the 3D charge-density wave in kagome metals

Abstract

The charge-density wave (CDW) mechanism and resulting structure of the AV3Sb5 family of kagome metals has posed a puzzling challenge since their discovery four years ago. In fact, the lack of consensus on the origin and structure of the CDW hinders the understanding of the emerging phenomena. Here, by employing a non-perturbative treatment of anharmonicity from first-principles calculations, we reveal that the charge-density transition in CsV3Sb5 is driven by the large electron-phonon coupling of the material and that the melting of the CDW state is attributed to ionic entropy and lattice anharmonicity. The calculated transition temperature is in very good agreement with experiments, implying that soft mode physics are at the core of the charge-density wave transition. Contrary to the standard assumption associated with a pure kagome lattice, the CDW is essentially three-dimensional as it is triggered by an unstable phonon at the L point. The absence of involvement of phonons at the M point enables us to constrain the resulting symmetries to six possible space groups. The unusually large electron-phonon linewidth of the soft mode explains why inelastic scattering experiments did not observe any softened phonon. We foresee that large anharmonic effects are ubiquitous and could be fundamental to understand the observed phenomena also in other kagome families.

8 pages, 5 figures

References in corpus (46)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Advanced capabilities for materials modelling with Quantum ESPRESSO
• 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
• Topological kagome magnets and superconductors
• Time-reversal symmetry-breaking charge order in a kagome superconductor
• Charge density waves and electronic properties of superconducting kagome metals
• Topological flat bands in frustrated kagome lattice CoSn
• Chiral flux phase in the Kagome superconductor AV${}_3$Sb${}_5$
• Analysis of Charge Order in the Kagome Metal $A$V${}_3$Sb${}_5$ ($A=$K,Rb,Cs)
• Nature of unconventional pairing in the kagome superconductors AV${}_3$Sb${}_5$
• Complex charge density waves at Van Hove singularity on hexagonal lattices: Haldane-model phase diagram and potential realization in kagome metals ${\text{AV}}_3{\text{Sb}}_5$
• Theoretical prediction of a strongly correlated Dirac metal
• Three-state nematicity and magneto-optical Kerr effect in the charge density waves in kagome superconductors
• The Stochastic Self-Consistent Harmonic Approximation: Calculating Vibrational Properties of Materials with Full Quantum and Anharmonic Effects
• Electronic nature of chiral charge order in the kagome superconductor CsV3Sb5
• Intertwined magnetism and charge density wave order in kagome FeGe
• Theory of the charge-density wave in $A$V${}_3$Sb${}_5$ kagome metals
• Coherent phonon spectroscopy and interlayer modulation of charge density wave order in the kagome metal CsV${}_3$Sb${}_5$
• Charge order breaks time-reversal symmetry in CsV${}_3$Sb${}_5$
• Electron-phonon coupling in the charge density wave state of CsV${}_3$Sb${}_5$
• Superconducting diode effect and interference patterns in Kagome CsV3Sb5
• Temperature-driven reorganization of electronic order in CsV${}_3$Sb${}_5$
• High Resolution Polar Kerr Effect Studies of CsV${}_3$Sb${}_5$: Tests for Time Reversal Symmetry Breaking Below the Charge Order Transition
• Quantum enhancement of charge density wave in NbS${}_2$ in the 2D limit
• Softening of a flat phonon mode in the kagome ScV${}_6$Sn${}_6$
• Coexistence of Multiple Stacking Charge Density Waves in Kagome Superconductor ${\mathrm{CsV}}_3{\mathrm{Sb}}_5$
• Weak Dimensionality Dependence and Dominant Role of Ionic Fluctuations in the Charge-Density-Wave Transition of NbSe${}_2$
• Correlated order at the tipping point in the kagome metal CsV${}_3$Sb${}_5$
• Phonon collapse and van der Waals melting of the 3D charge density wave of VSe${}_2$
• Order-disorder Peierls instability in the kagome metal (Cs,Rb)V${}_3$Sb${}_5$
• Electronic nematicity without charge density waves in titanium-based kagome metal
• Time-Dependent Self Consistent Harmonic Approximation: Anharmonic nuclear quantum dynamics and time correlation functions
• Charge-4e and charge-6e flux quantization and higher charge superconductivity in kagome superconductor ring devices
• The effect of the interlayer ordering on the Fermi surface of Kagome superconductor CsV${}_3$Sb${}_5$ revealed by quantum oscillations
• Interplay between Pair Density Wave and a Nested Fermi Surface
• Unconventional Optical Rotation in the Charge Ordered State of Kagome Metal CsV3Sb5
• Dynamical Study of the Origin of the Charge Density Wave in $A$V${}_3$Sb${}_5$ ($A=$K, Rb, Cs) Compounds
• Muon-spin relaxation study of the layered kagome superconductor CsV${}_3$Sb${}_5$
• 3D Fermi surfaces from charge order in layered CsV${}_3$Sb${}_5$
• Charge density wave and superconductivity in the kagome metal CsV${}_3$Sb${}_5$ around a pressure-induced quantum critical point
• Distinct switching of chiral transport in the kagome metals KV${}_3$Sb${}_5$ and CsV${}_3$Sb${}_5$
• Two elementary band representation model, Fermi surface nesting, and surface topological superconductivity in $A$V${}_3$Sb${}_5$ ($A=\text{K, Rb, Cs}$)
• Purely anharmonic charge-density wave in the 2D Dirac semimetal SnP

Cited by in corpus (8)

• Pressure-dependent Electronic Superlattice in the Kagome-Superconductor CsV${}_3$Sb${}_5$
• Origin of competing charge density waves in kagome metal ScV${}_6$Sn${}_6$
• Loop Current Order on the Kagome Lattice
• Charge-density-wave quantum critical point under pressure in 2$H$-TaSe${}_2$
• Symmetry-broken ground state and phonon mediated superconductivity in Kagome CsV${}_3$Sb${}_5$
• Emergent chirality and enantiomeric selectivity in layered NbOX${}_2$ crystals
• High-throughput study of kagome compounds in the AV3Sb5 family
• Electronic and structural properties of Rh- and Pd-based kagome layered shandites from first principles