Observation of anomalous amplitude modes in the kagome metal CsV${}_3$Sb${}_5$

Abstract

The charge-density wave (CDW) phase is often accompanied by the condensation of a soft acoustic phonon mode, giving rise to lattice distortion and charge density modulation. This picture was challenged for the recently discovered kagome metal CsV${}_3$Sb${}_5$, based on the evidence of absence of soft phonons. Here we report the observation of Raman-active CDW amplitude modes in this material, which are collective excitations typically thought to emerge out of frozen soft phonons. The amplitude modes strongly hybridize with other superlattice modes, imparting them with clear temperature-dependent frequency shift and broadening, rarely seen in other known CDW materials. Both the mode mixing and the large amplitude mode frequencies suggest that the CDW exhibits the character of strong electron-phonon coupling, a regime in which acoustic phonon softening can cease to exist. The observation of amplitude modes in the absence of soft phonons highlights the unconventional nature of the CDW in CsV${}_3$Sb${}_5$.

References in corpus (37)

• High temperature fractional quantum Hall states
• CsV${}_3$Sb${}_5$: a ${\mathbb{Z}}_2$ topological kagome metal with a superconducting ground state
• Fermi surface nesting and the origin of Charge Density Waves in metals
• 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
• Charge density waves and electronic properties of superconducting kagome metals
• Superconductivity in the ${\mathbb{Z}}_2$ kagome metal KV${}_3$Sb${}_5$
• Topological flat bands in frustrated kagome lattice CoSn
• Concurrence of anomalous Hall effect and charge density wave in a superconducting topological kagome metal
• 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
• Classification of Charge Density Waves Based on Their Nature
• 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
• 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
• Electronic nature of chiral charge order in the kagome superconductor CsV3Sb5
• s-wave superconductivity in kagome metal CsV${}_3$Sb${}_5$ revealed by ${}^{121/123}$Sb NQR and ${}^{51}$V NMR measurements
• Theory of the charge-density wave in $A$V${}_3$Sb${}_5$ kagome metals
• 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
• Coherent phonon spectroscopy and interlayer modulation of charge density wave order in the kagome metal CsV${}_3$Sb${}_5$
• Patterns and driving forces of dimensionality-dependent charge density waves in 2H-type transition metal dichalcogenides
• Electron-phonon coupling in the charge density wave state of CsV${}_3$Sb${}_5$
• Single-particle and collective mode couplings associated with 1- and 2-directional electronic ordering in metallic RTe${}_3$ (R = Ho, Dy, Tb)
• Possible star-of-David pattern charge density wave with additional modulation in the kagome superconductor CsV${}_3$Sb${}_5$
• Charge-Density-Wave-Induced Peak-Dip-Hump Structure and the Multiband Superconductivity in a Kagome Superconductor CsV${}_3$Sb${}_5$
• Low-energy optical properties of the non-magnetic kagome metal CsV${}_3$Sb${}_5$
• Giant Kohn anomaly and the phase transition in charge density wave ZrTe_3
• Wave vector dependent electron-phonon coupling drives charge-density-wave formation in TbTe3
• Quantum and classical mode softening near the charge-density-wave/superconductor transition of Cu${}_x$TiSe${}_2$: Raman spectroscopic studies
• Charge density wave order in kagome metal AV${}_3$Sb${}_5$ (A= Cs, Rb, K)
• Unconventional charge density wave and photoinduced lattice symmetry change in Kagome Metal CsV${}_3$Sb${}_5$ probed by time-resolved spectroscopy
• Manipulation of Jeff=3/2 states by tuning the tetragonal distortion
• Charge density waves and phonon-electron coupling in ZrTe${}_3$ investigated by Raman spectroscopy and first-principles calculations
• Origin of Charge Density Wave in Layered Kagome Metal CsV${}_3$Sb${}_5$

Cited by in corpus (6)

• Quantum states and intertwining phases in kagome materials
• Phonon promoted charge density wave in topological kagome metal ScV${}_6$Sn${}_6$
• Monolayer Kagome Metals AV${}_3$Sb${}_5$
• Origin and stability of the charge density wave in ScV${}_6$Sn${}_6$
• Direct Observation of Collective Modes of the Charge Density Wave in the Kagome Metal CsV${}_3$Sb${}_5$
• Intriguing kagome topological materials