Large Spontaneous Nonreciprocal Charge Transport in a Zero-Magnetization Antiferromagnet

Spontaneous breaking of time-reversal and spatial-inversion symmetries in solids triggers diverse intriguing phenomena. Although these phenomena have been extensively studied in insulators, similar investigations for metals remain limited. Herein, we report the observation and properties of spontaneous (i.e., zero-magnetic field) nonreciprocal charge transport in the zigzag intermetallic compound NdRu2Al10. This effect is attributed to the antiferromagnetic (AF) order, which can be interpreted as a magnetic toroidal dipole order. Our results reveal an excessively large nonreciprocal coefficient for this material, attributed to the strong effective magnetic field generated through c-f exchange interactions. The results also suggest that the nonreciprocal response of this material depends on the spin configurations of the AF domains. Overall, our findings are distinct from those previously reported for field-induced nonreciprocal charge transport and contribute to a comprehensive understanding of cross-correlations in symmetry-broken metals.