Direct observation of the collective modes of the charge density wave in the kagome metal CsV3Sb5

Doron Azoury; Alexander von Hoegen; Yifan Su; Kyoung Hun Oh; Tobias Holder; Hengxin Tan; Brenden R. Ortiz; Andrea Capa Salinas; Stephen D. Wilson; Binghai Yan; Nuh Gedik

doi:10.1073/pnas.2308588120

Direct observation of the collective modes of the charge density wave in the kagome metal CsV3Sb5

Doron Azoury, Alexander von Hoegen, Yifan Su, Kyoung Hun Oh, Tobias Holder, Hengxin Tan, Brenden R. Ortiz, Andrea Capa Salinas, Stephen D. Wilson, Binghai Yan, Nuh Gedik

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

6 Scopus citations

Abstract

A recently discovered group of kagome metals AV3Sb5 (A = K, Rb, Cs) exhibit a variety of intertwined unconventional electronic phases, which emerge from a puzzling charge density wave phase. Understanding of this charge-ordered parent phase is crucial for deciphering the entire phase diagram. However, the mechanism of the charge density wave is still controversial, and its primary source of fluctuations-the collective modes-has not been experimentally observed. Here, we use ultrashort laser pulses to melt the charge order in CsV3Sb5 and record the resulting dynamics using femtosecond angle-resolved photoemission. We resolve the melting time of the charge order and directly observe its amplitude mode, imposing a fundamental limit for the fastest possible lattice rearrangement time. These observations together with ab initio calculations provide clear evidence for a structural rather than electronic mechanism of the charge density wave. Our findings pave the way for a better understanding of the unconventional phases hosted on the kagome lattice.

Original language	English
Article number	e2308588120
Journal	Proceedings of the National Academy of Sciences of the United States of America
Volume	120
Issue number	40
DOIs	https://doi.org/10.1073/pnas.2308588120
State	Published - 2023
Externally published	Yes

Funding

ACKNOWLEDGMENTS. We thank Dongsung Choi, Baiqing Lyu, and Masataka Mogi for technical support. The work at MIT was supported by the US Department of Energy, BES DMSE (data taking, analysis, and manuscript writing) and Gordon and Betty Moore Foundation’s EPiQS Initiative grant GBMF9459 (instrumentation). D.A. acknowledges financial support by the Zuckerman STEM Leadership Program. A.v.H. gratefully acknowledges funding by the Humboldt Foundation. B.Y. acknowledges the financial support by the European Research Council (ERC Consolidator Grant “NonlinearTopo,” No. 815869) and the ISF– Personal Research Grant (No. 2932/21). S.D.W., B.R.O., and A.C.S. gratefully acknowledge support via the UC Santa Barbara NSF Quantum Foundry funded via the Q-AMASE-i program under award DMR-1906325.

Funders	Funder number
BES DMSE
UC Santa Barbara NSF	DMR-1906325
U.S. Department of Energy
Gordon and Betty Moore Foundation	GBMF9459
Alexander von Humboldt-Stiftung
Iowa Science Foundation	2932/21
Engineering Research Centers	815869
European Research Council

Keywords

ARPES
charge density wave
collective modes
kagome
ultrafast

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10.1073/pnas.2308588120

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Azoury, D., Hoegen, A. V., Su, Y., Oh, K. H., Holder, T., Tan, H., Ortiz, B. R., Salinas, A. C., Wilson, S. D., Yan, B., & Gedik, N. (2023). Direct observation of the collective modes of the charge density wave in the kagome metal CsV3Sb5. Proceedings of the National Academy of Sciences of the United States of America, 120(40), Article e2308588120. https://doi.org/10.1073/pnas.2308588120

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abstract = "A recently discovered group of kagome metals AV3Sb5 (A = K, Rb, Cs) exhibit a variety of intertwined unconventional electronic phases, which emerge from a puzzling charge density wave phase. Understanding of this charge-ordered parent phase is crucial for deciphering the entire phase diagram. However, the mechanism of the charge density wave is still controversial, and its primary source of fluctuations-the collective modes-has not been experimentally observed. Here, we use ultrashort laser pulses to melt the charge order in CsV3Sb5 and record the resulting dynamics using femtosecond angle-resolved photoemission. We resolve the melting time of the charge order and directly observe its amplitude mode, imposing a fundamental limit for the fastest possible lattice rearrangement time. These observations together with ab initio calculations provide clear evidence for a structural rather than electronic mechanism of the charge density wave. Our findings pave the way for a better understanding of the unconventional phases hosted on the kagome lattice.",

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AU - Azoury, Doron

AU - Hoegen, Alexander von

AU - Su, Yifan

AU - Oh, Kyoung Hun

AU - Holder, Tobias

AU - Tan, Hengxin

AU - Ortiz, Brenden R.

AU - Salinas, Andrea Capa

AU - Wilson, Stephen D.

AU - Yan, Binghai

AU - Gedik, Nuh

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N2 - A recently discovered group of kagome metals AV3Sb5 (A = K, Rb, Cs) exhibit a variety of intertwined unconventional electronic phases, which emerge from a puzzling charge density wave phase. Understanding of this charge-ordered parent phase is crucial for deciphering the entire phase diagram. However, the mechanism of the charge density wave is still controversial, and its primary source of fluctuations-the collective modes-has not been experimentally observed. Here, we use ultrashort laser pulses to melt the charge order in CsV3Sb5 and record the resulting dynamics using femtosecond angle-resolved photoemission. We resolve the melting time of the charge order and directly observe its amplitude mode, imposing a fundamental limit for the fastest possible lattice rearrangement time. These observations together with ab initio calculations provide clear evidence for a structural rather than electronic mechanism of the charge density wave. Our findings pave the way for a better understanding of the unconventional phases hosted on the kagome lattice.

AB - A recently discovered group of kagome metals AV3Sb5 (A = K, Rb, Cs) exhibit a variety of intertwined unconventional electronic phases, which emerge from a puzzling charge density wave phase. Understanding of this charge-ordered parent phase is crucial for deciphering the entire phase diagram. However, the mechanism of the charge density wave is still controversial, and its primary source of fluctuations-the collective modes-has not been experimentally observed. Here, we use ultrashort laser pulses to melt the charge order in CsV3Sb5 and record the resulting dynamics using femtosecond angle-resolved photoemission. We resolve the melting time of the charge order and directly observe its amplitude mode, imposing a fundamental limit for the fastest possible lattice rearrangement time. These observations together with ab initio calculations provide clear evidence for a structural rather than electronic mechanism of the charge density wave. Our findings pave the way for a better understanding of the unconventional phases hosted on the kagome lattice.

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Direct observation of the collective modes of the charge density wave in the kagome metal CsV3Sb5

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