Chiral spin texture in the anomalous Hall antiferromagnet CoNb₃S₆

CoNb₃S₆ (CNS) is an intercalated transition metal dichalcogenide exhibiting a large anomalous Hall effect (AHE) that cannot be explained by the collinear magnetic order previously observed by neutron diffraction. Thus, complex chiral, non-collinear, or non-coplanar spin orders have all been proposed as explanations for the observed large AHE in CNS. We carried out resonant elastic x-ray scattering (REXS) at the Co L₃ edge to obtain a complete description of the magnetic ordering in CNS. Using full linear polarization analysis, we found that the magnetic order is consistent with a single-Q multi-domain order rather than a multi-Q order. We also observed satellite peaks around the collinear wavevector, indicating a ∼30 nm uniaxial modulation of the collinear order. These satellites exhibit a circular dichroism, indicating a chiral magnetic structure. These results suggest that a long-range chiral spin texture provides the necessary symmetry-breaking mechanism for the large AHE in CNS.