Fig. 1. Electronic magnetochiral anisotropy and spontaneous symmetry breaking in CsV₃Sb₅.

a, Illustration of electrical resistance of normal and chiral conductors within the low-frequency limit. b, I(V) curve for a chiral conductor. In a d.c. measurement (left), the measured voltage displays a non-linear current dependence with magnetic field applied. In the a.c. case (right), the field-induced second-harmonic voltage, V_2ω, depends quadratically on the a.c. current I_ω. c, Different mechanisms for electronic magnetochiral anisotropy. The blue dashed line in the crystalline structure case represents the notation of helical atomic chains. For the case of scattering, the encircled hands represent the scattering centres with particular chirality. d, The crystal structure of CsV₃Sb₅ preserves all mirror symmetries at high temperatures and only spontaneous symmetry breaking at low temperatures enables a finite eMChA in a symmetric microstructure.