Persistence of charge density wave fluctuations in the absence of long-range order in a hole-doped kagome metal

Terawit Kongruengkit; Andrea N.Capa Salinas; Ganesh Pokharel; Brenden R. Ortiz; Stephen D. Wilson; John W. Harter

doi:10.1103/fzx6-hd1b

Persistence of charge density wave fluctuations in the absence of long-range order in a hole-doped kagome metal

Terawit Kongruengkit
, Andrea N.Capa Salinas
, Ganesh Pokharel
, Brenden R. Ortiz
, Stephen D. Wilson
, John W. Harter

Correlated Electron Materials

Research output: Contribution to journal › Article › peer-review

Abstract

The kagome metals AV3Sb5 (A=K, Rb, Cs) exhibit a complex interplay between charge density wave (CDW) order and superconductivity. In this study, we use ultrafast coherent phonon spectroscopy to probe the evolution of CDW order in hole-doped CsV3Sb5−xSnx across a broad range of compositions (0≤x≤0.68). While thermodynamic and diffraction measurements show long-range CDW order vanishes above x≈0.05, we observe persistent signatures of CDW fluctuations up to the highest doping levels, with correlation times on the order of several picoseconds. These results indicate the presence of a robust fluctuating charge order that survives well beyond the established CDW phase boundary. Furthermore, these fluctuations are enhanced near a doping-tuned quantum phase transition at x*≈0.15, which coincides with a local minimum in the superconducting Tc double-dome. Additional measurements on Ti- and K-substituted samples confirm that this behavior is intrinsic to hole doping and not tied to disorder. Overall, our findings suggest that CDW fluctuations play a central role in the electronic phase diagram of AV3Sb5 and may mediate or compete with superconductivity.

Original language	English
Article number	L022001
Journal	Physical Review Materials
Volume	10
Issue number	2
DOIs	https://doi.org/10.1103/fzx6-hd1b
State	Published - Feb 2026

Funding

This work was supported by the U.S. Air Force Office of Scientific Research (AFOSR) under Award No. FA9550-22-1-0270. Sample synthesis was supported by the National Science Foundation (NSF) through Enabling Quantum Leap: Convergent Accelerated Discovery Foundries for Quantum Materials Science, Engineering, and Information (Q-AMASE-i):Quantum Foundry at UC Santa Barbara (DMR-1906325). Work by B.R.O. was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division.Data availability. The data that support the findings of this article are not publicly available upon publication because it is not technically feasible, and/or the cost of preparing, depositing, and hosting the data would be prohibitive within the terms of this research project. The data are available from the authors upon reasonable request.

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10.1103/fzx6-hd1b

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title = "Persistence of charge density wave fluctuations in the absence of long-range order in a hole-doped kagome metal",

abstract = "The kagome metals AV3Sb5 (A=K, Rb, Cs) exhibit a complex interplay between charge density wave (CDW) order and superconductivity. In this study, we use ultrafast coherent phonon spectroscopy to probe the evolution of CDW order in hole-doped CsV3Sb5−xSnx across a broad range of compositions (0≤x≤0.68). While thermodynamic and diffraction measurements show long-range CDW order vanishes above x≈0.05, we observe persistent signatures of CDW fluctuations up to the highest doping levels, with correlation times on the order of several picoseconds. These results indicate the presence of a robust fluctuating charge order that survives well beyond the established CDW phase boundary. Furthermore, these fluctuations are enhanced near a doping-tuned quantum phase transition at x*≈0.15, which coincides with a local minimum in the superconducting Tc double-dome. Additional measurements on Ti- and K-substituted samples confirm that this behavior is intrinsic to hole doping and not tied to disorder. Overall, our findings suggest that CDW fluctuations play a central role in the electronic phase diagram of AV3Sb5 and may mediate or compete with superconductivity.",

author = "Terawit Kongruengkit and Salinas, \{Andrea N.Capa\} and Ganesh Pokharel and Ortiz, \{Brenden R.\} and Wilson, \{Stephen D.\} and Harter, \{John W.\}",

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AU - Kongruengkit, Terawit

AU - Salinas, Andrea N.Capa

AU - Pokharel, Ganesh

AU - Ortiz, Brenden R.

AU - Wilson, Stephen D.

AU - Harter, John W.

PY - 2026/2

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N2 - The kagome metals AV3Sb5 (A=K, Rb, Cs) exhibit a complex interplay between charge density wave (CDW) order and superconductivity. In this study, we use ultrafast coherent phonon spectroscopy to probe the evolution of CDW order in hole-doped CsV3Sb5−xSnx across a broad range of compositions (0≤x≤0.68). While thermodynamic and diffraction measurements show long-range CDW order vanishes above x≈0.05, we observe persistent signatures of CDW fluctuations up to the highest doping levels, with correlation times on the order of several picoseconds. These results indicate the presence of a robust fluctuating charge order that survives well beyond the established CDW phase boundary. Furthermore, these fluctuations are enhanced near a doping-tuned quantum phase transition at x*≈0.15, which coincides with a local minimum in the superconducting Tc double-dome. Additional measurements on Ti- and K-substituted samples confirm that this behavior is intrinsic to hole doping and not tied to disorder. Overall, our findings suggest that CDW fluctuations play a central role in the electronic phase diagram of AV3Sb5 and may mediate or compete with superconductivity.

AB - The kagome metals AV3Sb5 (A=K, Rb, Cs) exhibit a complex interplay between charge density wave (CDW) order and superconductivity. In this study, we use ultrafast coherent phonon spectroscopy to probe the evolution of CDW order in hole-doped CsV3Sb5−xSnx across a broad range of compositions (0≤x≤0.68). While thermodynamic and diffraction measurements show long-range CDW order vanishes above x≈0.05, we observe persistent signatures of CDW fluctuations up to the highest doping levels, with correlation times on the order of several picoseconds. These results indicate the presence of a robust fluctuating charge order that survives well beyond the established CDW phase boundary. Furthermore, these fluctuations are enhanced near a doping-tuned quantum phase transition at x*≈0.15, which coincides with a local minimum in the superconducting Tc double-dome. Additional measurements on Ti- and K-substituted samples confirm that this behavior is intrinsic to hole doping and not tied to disorder. Overall, our findings suggest that CDW fluctuations play a central role in the electronic phase diagram of AV3Sb5 and may mediate or compete with superconductivity.

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Persistence of charge density wave fluctuations in the absence of long-range order in a hole-doped kagome metal

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