Switchable chiral transport in charge-ordered kagome metal CsV₃Sb₅

When electric conductors differ from their mirror image, unusual chiral transport coefficients appear that are forbidden in achiral metals, such as a non-linear electric response known as electronic magnetochiral anisotropy (eMChA)^1-6. Although chiral transport signatures are allowed by symmetry in many conductors without a centre of inversion, they reach appreciable levels only in rare cases in which an exceptionally strong chiral coupling to the itinerant electrons is present. So far, observations of chiral transport have been limited to materials in which the atomic positions strongly break mirror symmetries. Here, we report chiral transport in the centrosymmetric layered kagome metal CsV₃Sb₅ observed via second-harmonic generation under an in-plane magnetic field. The eMChA signal becomes significant only at temperatures below [Formula: see text] 35 K, deep within the charge-ordered state of CsV₃Sb₅ (T_CDW ≈ 94 K). This temperature dependence reveals a direct correspondence between electronic chirality, unidirectional charge order⁷ and spontaneous time-reversal symmetry breaking due to putative orbital loop currents^8-10. We show that the chirality is set by the out-of-plane field component and that a transition from left- to right-handed transport can be induced by changing the field sign. CsV₃Sb₅ is the first material in which strong chiral transport can be controlled and switched by small magnetic field changes, in stark contrast to structurally chiral materials, which is a prerequisite for applications in chiral electronics.