1. Direct Observation of Collective Modes of the Charge Density Wave in the Kagome Metal CsV$_3$Sb$_5$
- Author
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Azoury, Doron, von Hoegen, Alexander, Su, Yifan, Oh, Kyoung Hun, Holder, Tobias, Tan, Hengxin, Ortiz, Brenden R., Salinas, Andrea Capa, Wilson, Stephen D., Yan, Binghai, and Gedik, Nuh
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Strongly Correlated Electrons (cond-mat.str-el) ,FOS: Physical sciences ,Physics - Optics ,Optics (physics.optics) - Abstract
A new group of kagome metals AV$_3$Sb$_5$ (A = K, Rb, Cs) exhibit a variety of intertwined unconventional electronic phases, which emerge from a puzzling charge density wave phase. Understanding of this parent charge order 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 - have not been experimentally observed. Here, we use ultrashort laser pulses to melt the charge order in CsV$_3$Sb$_5$ 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 better understanding of the unconventional phases hosted on the kagome lattice., Comment: 17 pages, 4 figures
- Published
- 2023
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