Selectable Growth and Electronic Structures of Monolayer 1T-VSe2 and V5Se8 Films on Bilayer Graphene

Intercalating magnetic atoms in 2D transition-metal dichalcogenides (TMDCs) is a feasible route for fabricating 2D magnetic materials. As a 2D-TMDC, the ground state of monolayer (ML) 1T-VSe2 should be the charge-density-wave state rather than the ferromagnetic state. In this study, magnetism is induced in 1T-VSe2 via the realization of selectable molecular beam epitaxial growth of both ML 1T-VSe2 and ML V5Se8 films on a bilayer graphene substrate. The morphologies of the grown 1T-VSe2 and V5Se8 films are characterized using scanning tunneling microscope, which showed differences in the heights of the domains. Subsequently, combining in situ X-Ray photoemission spectroscopy measurements, it is determined that the grown V5Se8 film contained 26.7% more V atoms than the 1T-VSe2 film, thereby confirming the chemical stoichiometry of the created samples. In addition, using in situ angle-resolved photoemission spectroscopy measurements, the different electronic structures of the ML 1T-VSe2 and ML V5Se8 films are studied. The results obtained indicate that the method applied is an effective way for realizing selective growth of 1T-VSe2 or V5Se8 films, while providing significant information on their electronic structure differences, which can aid in investigating the magnetic properties of V5Se8.