  Combining magnetism with band topology provides various novel phases that are
otherwise impossible. Among several cases, noncollinear metallic
antiferromagnets can reveal particularly rich topological physics due to their
diverse magnetic ground states. However, there are only a few experimental
studies due to the lack of suitable materials, especially with triangular
lattice antiferromagnets. Here, we report that metallic triangular
antiferromagnet Co1/3TaS2 exhibits a substantial anomalous Hall effect (AHE)
related to its noncollinear magnetic order. Our first-principles calculations
found that hourglass Weyl fermions from the non-symmorphic symmetry trigger
AHE. We further show that AHE in Co1/3TaS2 can be characterized by the toroidal
moment, a vortex-like multipole component that arises from a combination of
chiral lattice and geometrical frustration. Finally, the unusual
field-tunability of the toroidal moment puts Co1/3TaS2 as a rare example of a
noncollinear metallic antiferromagnet filled with interesting magnetic and
topological properties.
