Electronic chirality in the metallic ferromagnet Fe 1 / 3 TaS 2

We bring together optical spectroscopy and first-principles calculations to reveal the electronic properties of the chiral ferromagnet ${\mathrm{Fe}}_{1/3}{\mathrm{TaS}}_{2}$. Signatures of chirality are superimposed upon a complex free-carrier response that emanates from both Ta and Fe bands. These include a honeycomb charge density pattern in the Fe layer and a hole $\ensuremath{\rightarrow}$ electron pocket crossover at the K point, low-energy excitations between spin split bands that cross the Fermi surface, and clustered rather than well-separated on-site and charge-transfer excitations. These findings advance the understanding of intercalation and symmetry breaking on the fundamental excitations in metallic chalcogenides.