Evidence of a distinct collective mode in Kagome superconductors

Abstract

The collective modes of the superconducting order parameter fluctuation can provide key insights into the nature of the superconductor. Recently, a family of superconductors has emerged in non-magnetic kagome material AV3Sb5 (A=K, Rb, Cs), exhibiting fertile emergent phenomenology. However, the collective behaviors of Cooper pairs have not been studied. Here, we report a distinct collective mode in CsV3-xTaxSb5 using scanning tunneling microscope/spectroscopy. The spectral line-shape is well-described by one isotropic and one anisotropic superconducting gap, and a bosonic mode due to electron-mode coupling. With increasing x, the two gaps move closer in energy, merge into two isotropic gaps of equal amplitude, and then increase synchronously. The mode energy decreases monotonically to well below 2Δ and survives even after the charge density wave order is suppressed. We propose the interpretation of this collective mode as Leggett mode between different superconducting components or the Bardasis-Schrieffer mode due to a subleading superconducting component.

11 pages, 4 figures

References in corpus (43)

• High temperature fractional quantum Hall states
• CsV${}_3$Sb${}_5$: a ${\mathbb{Z}}_2$ topological kagome metal with a superconducting ground state
• Tunable Phase Boundaries and Ultra-Strong Coupling Superconductivity in Mirror Symmetric Magic-Angle Trilayer Graphene
• Discovery of unconventional chiral charge order in kagome superconductor KV3Sb5
• Roton pair density wave and unconventional strong-coupling superconductivity in a topological kagome metal
• Time-reversal symmetry-breaking charge order in a kagome superconductor
• Superconductivity in the ${\mathbb{Z}}_2$ kagome metal KV${}_3$Sb${}_5$
• Negative flat band magnetism in a spin-orbit coupled correlated kagome magnet
• Three-dimensional charge density wave and robust zero-bias conductance peak inside the superconducting vortex core of a kagome superconductor CsV${}_3$Sb${}_5$
• Amplitude / Higgs Modes in Condensed Matter Physics
• Interplay of electron-lattice interactions and superconductivity in Bi2Sr2CaCu2O8+d
• Rotation symmetry breaking in the normal state of a kagome superconductor KV3Sb5
• Multiband superconductivity with sign-preserving order parameter in kagome superconductor CsV3Sb5
• Twofold symmetry of $c$-axis resistivity in topological kagome superconductor CsV${}_3$Sb${}_5$ with in-plane rotating magnetic field
• Three-state nematicity and magneto-optical Kerr effect in the charge density waves in kagome superconductors
• AV${}_3$Sb${}_5$ Kagome Superconductors: Progress and Future Directions
• Observation of Leggett's collective mode in a multi-band MgB2 superconductor
• Anisotropic superconducting properties of Kagome metal CsV3Sb5
• Nodeless electron pairing in CsV${}_3$Sb${}_5$-derived kagome superconductors
• Visualizing the Energy-gap Modulations of the Cuprate Pair Density Wave State
• Resonance in the electron-doped high-Tc superconductor Pr0.88LaCe0.12CuO(4-delta)
• Chern Fermi pocket, topological pair density wave, and charge-4e and charge-6e superconductivity in kagome superconductors
• Microscopic evidence for anisotropic multigap superconductivity in the CsV${}_3$Sb${}_5$ kagome superconductor
• Superconducting diode effect and interference patterns in Kagome CsV3Sb5
• Low-energy optical properties of the non-magnetic kagome metal CsV${}_3$Sb${}_5$
• A distinct bosonic mode in an electron-doped high-transition-temperature superconductor
• Bulk evidence of anisotropic $s$-wave pairing with no sign change in the kagome superconductor CsV${}_3$Sb${}_5$
• Visualizing the periodic modulation of Cooper pairing in a severely underdoped cuprate
• A unique van Hove singularity in kagome superconductor CsV${}_{3-x}$Ta${}_x$Sb${}_5$ with enhanced superconductivity
• Localized spin-orbit polaron in magnetic Weyl semimetal Co${}_3$Sn${}_2$S${}_2$
• Smectic Pair Density Wave Order in EuRbFe4As4
• Light Quantum Control of Persisting Higgs Modes in Iron-Based Superconductors
• Evidence of a spin resonance mode in the iron-based superconductor Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ from scanning tunneling spectroscopy
• Unidirectional coherent quasiparticles in the high-temperature rotational symmetry broken phase of AV3Sb5 kagome superconductors
• Axial Higgs Mode Detected by Quantum Pathway Interference in RTe3
• Observation of superconducting collective modes from competing pairing instabilities in single-layer NbSe${}_2$
• Puddle formation, persistent gaps, and non-mean-field breakdown of superconductivity in overdoped (Pb,Bi)2Sr2CuO6+δ
• Unconventional superconductivity protected from disorder on the kagome lattice
• Role of Inelastic Tunneling through the Barrier in Scanning Tunneling Microscope Experiments on Cuprates
• Dynamic Superconductivity Responses in Photo-excited Optical Conductivity and Nernst Effect
• Strong-coupling superconductivity and weak vortex pinning in Ta-doped CsV${}_3$Sb${}_5$ single crystals
• Classification of Lifshitz invariant in multiband superconductors: an application to Leggett modes in the linear response regime in Kagome lattice models
• Detection of collective modes in unconventional superconductors using tunneling spectroscopy

Cited by in corpus (6)

• Observation of Fermi-surface-dependent anisotropic Cooper pairing in kagome superconductor CsV3Sb5
• Optically active Higgs and Leggett modes in multiband pair-density-wave superconductors with Lifshitz invariant
• Impact of Charge Density Waves on Superconductivity and Topological Properties in AV${}_3$Sb${}_5$ Kagome Superconductors
• Josephson spectroscopy study of kagome superconductors toward the deep point-contact regime
• Hybrid collective excitations in topological superconductor/ferromagnetic insulator heterostructures
• Enhanced Coupling of Superconductivity and Evolution of Gap Structure in CsV3Sb5 through Ta Doping