Probing the Anomalous Symmetry Breaking in Kagome Material CsV3Sb5 via Third-Order Nonlinearity

The kagome material has rapidly established itself as a research frontier in condensed matter physics, owing to its distinctive geometric structure and the rich array of unconventional physical phenomena. In the kagome AV3Sb5 (A = K, Rb, and Cs) family, the charge-ordered state exhibits a remarkable characteristic, i.e., anomalous symmetry breaking, which is tied to the topological nature of the electronic band structure. Here, we report the third-order nonlinear longitudinal and Hall responses that persist stably up to room temperature in the kagome material CsV3Sb5. Notably, the nonlinear responses demonstrate significant transition below the charge density wave (∼77 K) order and anomalous symmetry-breaking (∼39 K) state. The scaling analysis indicates that the third-order nonlinear transport is governed jointly by the quantum geometric contribution and extrinsic scattering. This study advances the understanding of the third-order nonlinear transport and provides a distinct method to detect anomalous symmetry breaking in CsV3Sb5.