Absence of E 2 g Nematic Instability and Dominant A 1 g Response in the Kagome Metal CsV 3 Sb 5

• Published in: Physical review. X 2024-07, Vol.14 (3), Article 031015
• Main Authors: Liu, Zhaoyu, Shi, Yue, Jiang, Qianni, Rosenberg, Elliott W., DeStefano, Jonathan M., Liu, Jinjin, Hu, Chaowei, Zhao, Yuzhou, Wang, Zhiwei, Yao, Yugui, Graf, David, Dai, Pengcheng, Yang, Jihui, Xu, Xiaodong, Chu, Jiun-Haw
• Format: Article
• Language: English
• ISSN: 2160-3308; 2160-3308
• DOI: 10.1103/PhysRevX.14.031015

Ever since the discovery of the charge density wave (CDW) transition in the kagome metal CsV 3 Sb 5 , the nature of its symmetry breaking has been 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 has been reported based on the diverging elastoresistivity coefficient in the anisotropic channel ( m E 2 g ). 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 low-temperature superconductivity. Here, we report elastoresistivity measurements of CsV 3 Sb 5 using three different techniques probing both isotropic and anisotropic symmetry channels. Contrary to previous reports, we find the anisotropic elastoresistivity coefficient m E 2 g 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 show no enhancement associated with nematic susceptibility. On the other hand, the symmetric elastoresistivity coefficient m A 1 g 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 A 1 g channel.