Electronic Fingerprints of 3Q Magnetic Order in a van der Waals Magnet - CoxTaS2

Magnetically intercalated transition-metal dichalcogenides are emerging as a rich platform for exploring exotic quantum states in van der Waals magnets. Among them, CoxTaS2 has attracted intense interest following the recent discovery of a distinctive 3Q antiferromagnetic ground state and a pronounced topological Hall effect below a critical doping near x~1/3, both intimately tied to the cobalt concentration. To date, direct evidence of this enigmatic 3Q magnetic order in the electronic structure, however, has remained elusive. Here we report a comprehensive angle-resolved photoemission spectroscopy study of CoxTaS2 across compositions near x~1/3. We uncover the long-sought fingerprints of 3Q magnetic order in the electronic structure. These features are consistent with theoretical predictions for a 3Q magnetic order near three-quarters band filling on a cobalt triangular lattice. Taken together, our results provide evidence of 3Q magnetic order in the electronic structure, establishing TMD van der Waals magnets as tunable materials to explore the interplay between magnetism and band topology.