Absence of E_{2g} Nematic Instability and Dominant A_{1g} Response in the Kagome Metal CsV_{3}Sb_{5}

Abstract

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_{2g}}). 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_{2g}} 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_{1g}} 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_{1g} channel.