Atomistic real-space observation of the van der Waals layered structure and tailored morphology in VSe2

Abstract

Two-dimensional (2D) transition metal dichalcogenides with van der Waals gaps have attracted much attention due to their peculiarly distinctive physical properties from their bulk counterparts. Among them, vanadium diselenide (VSe₂) has been considered to be a promising candidate for future spintronic devices, as room temperature ferromagnetism was reported recently. However, detailed crystallography and properties of VSe₂ nanosheets have been less explored. Here, we report the atomistic real-space observation of the van der Waals layered structure of VSe₂ for the first time. Furthermore, simply by controlling the carrier gas flow rate, a morphological variation of the surface area and thickness of VSe₂ nanosheets was observed. The room temperature ferromagnetic feature of single VSe₂ nanosheets was also revealed by magnetic force microscopy measurements. Our findings will play a significant role in the research of intrinsic 2D ferromagnetic materials.