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10.35097/2kxzs0g0n3z2v52f2026-05-13T13:58:36Zradar4kit

10.35097/2kxzs0g0n3z2v52f McGuinness, Philippa Helen Philippa Helen McGuinness Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT) Henssler, Fabian Fabian Henssler 0009-0002-3200-6477 Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT) Alkorta, Manex Manex Alkorta Westarp, Mark Joachim Graf, von Mark Joachim Graf Westarp Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT) Korshunov, Artem Artem Korshunov Bosak, Alexei Alexei Bosak Ishikawa, Daisuke Daisuke Ishikawa Baron, Alfred Q. R. Alfred Q. R. Baron Merz, Michael Michael Merz Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT), Karlsruhe Nano Micro Facility (KNMF), Karlsruher Institut für Technologie (KIT) Haghighirad, Amir-Abbas Amir-Abbas Haghighirad Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT) Vergniory, Maia G. Maia G. Vergniory Souliou, Sofia-Michaela Sofia-Michaela Souliou Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT) Heid, Rolf Rolf Heid 0000-0002-2144-1417 Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT) Errea, Ion Ion Errea Le Tacon, Matthieu Matthieu Le Tacon 0000-0002-5838-3724 Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT) Karlsruhe Institute of Technology 2024 2026 Physics Kagome Soft Phonon Superconductivity CDW Open Access Creative Commons Attribution 4.0 International McGuinness, Philippa Helen Henssler, Fabian 0009-0002-3200-6477 Alkorta, Manex Westarp, Mark Joachim Graf, von Korshunov, Artem Bosak, Alexei Ishikawa, Daisuke Baron, Alfred Q. R. Merz, Michael Haghighirad, Amir-Abbas Vergniory, Maia G. Souliou, Sofia-Michaela Heid, Rolf 0000-0002-2144-1417 Errea, Ion Le Tacon, Matthieu 0000-0002-5838-3724 Charge-density-wave (CDW) order and superconductivity coexist in the kagome metals AV₃Sb₅~(A=K, Cs, Rb), raising fundamental questions about the mechanisms driving their intertwined phases. Here we combine high-resolution inelastic X-ray scattering with first-principles calculations to uncover the origin of CDW formation in CsV₃Sb₅. Guided by structure factor analysis, we identify a soft phonon mode along the reciprocal $\textit{M}-\textit{L}$ direction, with the strongest effect at the $\textit{L}$ point, where the elastic scattering intensity also grows most rapidly upon cooling. First-principles calculations incorporating lattice anharmonicity and electron-phonon coupling reproduce these observations and establish a soft-mode instability at the $\textit{L}$ point as the driving mechanism of CDW formation. Despite the weakly first-order character of the transition, our results unambiguously demonstrate that the CDW in CsV₃Sb₅ originates from a softened phonon, clarifying its microscopic origin and highlighting the central role of lattice dynamics in kagome metals. Charge-density-wave (CDW) order and superconductivity coexist in the kagome metals AV₃Sb₅~(A=K, Cs, Rb), raising fundamental questions about the mechanisms driving their intertwined phases. Here we combine high-resolution inelastic X-ray scattering with first-principles calculations to uncover the origin of CDW formation in CsV₃Sb₅. Guided by structure factor analysis, we identify a soft phonon mode along the reciprocal $\textit{M}-\textit{L}$ direction, with the strongest effect at the $\textit{L}$ point, where the elastic scattering intensity also grows most rapidly upon cooling. First-principles calculations incorporating lattice anharmonicity and electron-phonon coupling reproduce these observations and establish a soft-mode instability at the $\textit{L}$ point as the driving mechanism of CDW formation. Despite the weakly first-order character of the transition, our results unambiguously demonstrate that the CDW in CsV₃Sb₅ originates from a softened phonon, clarifying its microscopic origin and highlighting the central role of lattice dynamics in kagome metals. Figure 1: Calculation results on reasonable request Figure 2: Find the raw data in ESRF DS Figure 3: Find the raw data in RIKEN IXS: a,b,d,f --> A06; c,e --> A38 Figure 4: Find the raw data in RIKEN IXS (A06) Calculation results on reasonable request Figure 5: Find the raw data in RIKEN IXS (A06) Calculation results on reasonable request Figure S1: Calculation results on reasonable request Figure S2: Calculation results on reasonable request Figure S3: Calculation results on reasonable request Figure S4: Find the raw data in ESRF IXS --> timescan in spec document, a cryostream was used Figure S5: Find the raw data in RIKEN IXS (A06) Figure S6: Find the raw data in RIKEN IXS (A06) Figure S7: Find the raw data in RIKEN IXS (A06) Figure S8: Find the raw data in ESRF DS Figure S9: Find the raw data in ESRF IXS (A2) Figure S10: Calculation results on reasonable request https://publikationen.bibliothek.kit.edu/1000192987 3,9 GB application/x-tar