Ultrafast quasiparticle dynamics and collective excitations in CsV3Sb5

Zhengxing Wei; Liang Cheng; Jingbo Qi

doi:10.1117/12.3025385

24 June 2024 Ultrafast quasiparticle dynamics and collective excitations in CsV₃Sb₅

Zhengxing Wei, Liang Cheng, Jingbo Qi

Proceedings Volume 13209, 2nd International Conference on UltrafastX 2023; 1320909 (2024) https://doi.org/10.1117/12.3025385
Event: 2nd International Conference on UltrafastX 2023 (UX2023), 2023, Xi'an, China

Abstract

CsV₃Sb₅ is a recently discovered Kagome metal that exhibits a combination of superconductivity with a critical temperature (T_C) of 2.5 K and charge density wave (CDW) order at T_CDW = 94 K. In this study, we investigate the collective excitations and quasiparticle dynamics in CsV₃Sb₅ using ultrafast optical pump-probe spectroscopy. According to our results, in addition to the CDW phase related electron and coherent phonon dynamics, we found another electronic symmetry breaking by nematic phase transition at T* ( 20 K), which can mediate the relaxation of carriers. At temperature below T*, a gap about 4 meV related to the nematic order is open, which determines the low-temperature dynamics of carriers in the rst 2 picosecond (ps). Moreover, we also observed the abrupt change of electron dynamics caused by the CDW phase transition at T_CDW. Furthermore, we identify the presence of a CDW induced mode at 1.3 THz below T_CDW, as well as two collective modes at 3.1 THz and 3.8 THz below 80 K. It is noteworthy that these two collective modes appear to be associated with the breaking of C₆ rotational symmetry. These observations suggest the rich phase order below T_CDW and emphasize the need for a deeper understanding of CDW and nematicity order in the Kagome metals.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Zhengxing Wei, Liang Cheng, and Jingbo Qi "Ultrafast quasiparticle dynamics and collective excitations in CsV₃Sb₅", Proc. SPIE 13209, 2nd International Conference on UltrafastX 2023, 1320909 (24 June 2024); https://doi.org/10.1117/12.3025385

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