Fermiology of a topological, intercalated transition metal dichalcogenide compound

Transition metal dichalcogenides (TMDs) are known to have various phases such as charge density waves, superconductivity and Mott insulating phases. Here, we study the electronic structure of a transition metal dichalcogenide intercalated by triangular layers of Co atoms using angle-resolved photoemission spectroscopy. The measured Fermi surfaces after intercalation are different from pristine compounds and cannot be explained by a simple rigid band shift. Interestingly, recently a large anomalous hall effect (AHE) was observed in this family [1]. We found that AHE values can change signs with different intercalation levels. We utilize ARPES to track the Fermi level shifting with different dopings. Our study suggests the possibility of a tunable AHE system. Temperature dependence measurement also reveals how band structure changes across the magnetic transition. Finally, we conduct photon energy dependence to demonstrate the nontrivial band crossing. Our ARPES study indicates that this intercalated TMD compound hosts rich physics such as magnetism, tunable AHE and nontrivial band topology.