Heteroepitaxial growth of single layer ferromagnetic VSe₂ on graphene and Bi₂Se₃

Recent work has shown evidence of ferromagnetic order at room temperature in epitaxial single layer VSe₂, providing promising opportunities for emergent properties particularly when integrated with other 2D materials. In this work, we report the results of the heteroepitaxial growth of VSe₂ on epitaxial graphene/6H-SiC(0001) and topological insulator Bi₂Se₃. Using in situ scanning tunneling microscopy, we find markedly different growth behaviors on these two substrates. On top of graphene, hexagonal VSe₂ islands first nucleate randomly within the terraces, and then coalesce to form single layer VSe₂ upon further growth. In contrast, the epitaxial Bi₂Se₃(111) substrate surface exhibits spirals with atomically smooth terraces up to 50 nm in width. Here, the VSe₂ epilayer preferentially nucleates at the Bi₂Se₃ spiral step edges forming a distinct lateral Bi₂Se₃ -VSe₂ heterojunctions. This growth mode of VSe₂ on Bi₂Se₃ provides unique opportunities to explore one-dimensional topological-magnetic heterostructures whose structural and electronic properties will be discussed at the meeting.