Key points are not available for this paper at this time.
Abstract Antiferromagnets with broken time‐reversal () symmetry (‐odd antiferromagnets) have gained extensive attention, mainly due to their ferromagnet‐like behavior despite the absence of net magnetization. However, certain types of ‐odd antiferromagnets remain inaccessible by the typical ferromagnet‐like phenomena (e.g., anomalous Hall effect). One such system is characterized by a ‐odd scalar quantity, the magnetic toroidal monopole. To access the broken symmetry in such a system, a unique nonreciprocal optical phenomenon, electric field‐induced nonreciprocal directional dichroism ( E ‐induced NDD), is employed. Signals of E ‐induced NDD are successfully detected in a ‐odd antiferromagnet, Co₂SiO₄, whose magnetic structure is characterized by the magnetic toroidal monopole. Furthermore, by spatially resolving the E ‐induced NDD, spatial distributions of a pair of domain states related to one another by the operation are visualized. The domain imaging revealed the inversion of the domain pattern by applying a magnetic field, which is explained by trilinear coupling attributed to the piezomagnetic effect. The observation of E ‐induced NDD highlights unique functionalities of ‐odd antiferromagnets.
Hayashida et al. (Wed,) studied this question.