Spin-polarized van Hove singularity and Berry-curvature hotspot in a chiral antiferromagnet Co_1/3TaS₂

Chiral spin textures in non-coplanar magnets are a source of Berry curvature, generating anomalous Hall response even at zero net magnetization. Yet direct spin-resolved evidence connecting the real-space magnetic texture to the momentum-space Berry curvature that underpins this response has remained elusive. Here we report the observation of the chiral non-coplanar order in Co1/3TaS2 and resultant spin-split van Hove singularities(vHS) near the Fermi level. Using spin-polarized scanning tunneling microscopy (SP-STM), a pronounced real-space modulation in spin current is observed, whereas the charge current shows no such counterpart. Symmetry analysis shows that this signal is allowed only in the non-coplanar chiral triple-Q state and is forbidden in single- or double-Q textures. The spin splitting of vHS with its flat dispersion account for the dominant source of Berry curvature. Taken together, our discovery of spin-split van Hove singularities provides a microscopic origin for the large anomalous Hall response reported in this material. Non-coplanar chiral magnets thus emerge as a platform to engineer Berry-curvature-driven fermiology and correlated phenomena.