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RCQM/FCMP: Jiun-Haw Chu: Absence of nematic instability in the kagome metal CsV3Sb5

Talk Date: Tuesday, 11/28/2023, 2:30 PM (CST) Speaker: Jiun-Haw Chu Institution: University of Washington, Seattle Title: Absence of nematic instability in the kagome metal CsV3Sb5 Abstract: Ever since the discovery of the charge density wave (CDW) transition in the kagome metal CsV3Sb5, the nature of its symmetry breaking is under intense debate. While evidence suggests that the rotational symmetry is already broken at the CDW transition temperature (T_CDW ), an additional electronic nematic instability well below T_CDW was reported based on the diverging elastoresistivity coefficient in the anisotropic channel (mE2g ). Verifying the existence of a nematic transition below T_CDW is not only critical for establishing the correct description of the CDW order parameter, but also important for understanding the low-temperature superconductivity. In this talk, I will present the measurements of elastoresistivity of CsV3Sb5 using three different techniques probing both isotropic and anisotropic symmetry channels. Contrary to previous reports, we found the anisotropic elastoresistivity coefficient m E2g is temperature-independent except for a step jump at T_CDW . The absence of nematic fluctuations is further substantiated by measurements of the elastocaloric effect, which shows no enhancement associated with a nematic susceptibility. On the other hand, the symmetric elastoresistivity coefficient m A1g increases below T_CDW, reaching a peak value of 90 at T∗ = 20 K. Our results strongly indicate that the phase transition at T∗ is not nematic in nature and the previously reported diverging elastoresistivity is due to the contamination from the A1g channel. References: [1] Z. Liu, et. al. arXiv:2309.14574 (2023).