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

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.