Chirality, a widely existing material property in nature that involves breaking the left-right symmetry, has had profound influence on various fields of natural sciences. Nonlinear responses, such as electronic magnetochiral anisotropy (eMChA), have been recognized as sensitive probes for the effects of symmetry breaking and nontrivial quantum geometries in solids. So far, observations of eMChA have primarily been limited to inversion-symmetry broken materials. Here, we report a remarkable chiral transport in centrosymmetric candidate topological superconductor 2M-WS₂ flakes observed via second-harmonic generation under an out-of-plane magnetic field. More importantly, eMChA becomes significant around the crossover temperature T_FL~25K from the Fermi liquid (FL) to strange metal (SM) in the normal state, which interestingly echoes the anomalously large Nernst response at the same temperature in bulk 2M-WS₂. These observations reveal a direct correspondence between the nonlinear response, Nernst response, and FL-SM transition in 2M-WS₂. Theoretical analysis indicates that nontrivial quantum geometry is behind the simultaneous response of eMChA and Nernst effects in 2M-WS₂ and the contribution from the orbital magnetic moment at the Fermi surface becomes significant during the FL-SM transition. Based on first-principles calculations, a thick-layer-sliding mechanism with minimal energy gain in 2M-WS₂ provides one possibility for the generation of such nontrivial quantum geometry. The intertwined physics of the remarkable eMChA, Nernst response, and FL-SM transition make 2M-WS₂ a rare quantum platform to study the chiral transport and unexplored phenomena in strange metals, which may shed light on one of the trans-century unresolved scientific issues with unconventional high-temperature superconductivity.

Paper link: https://journals.aps.org/prl/abstract/10.1103/43cm-lhrk