Identification of a low-energy metastable 1T-type phase for monolayer VSe2

Elucidating the polymorphism of transition metal dichalcogenide layers and the interplay between structure and properties is a key challenge for the application of these materials. We identify a low-energy metastable phase of monolayer VSe2 and elucidate its magnetic and electronic properties. This structure is distinct from the previously identified charge density wave (CDW) phase. However, while having rather distinct properties it is very close in energy to the CDW phase and is likely to be realized in experiments. Importantly, local bonding instabilities, as characterized by reconstruction of the electronic structure over a wide energy range, are important for this distortion, which includes both V off-centering in the octahedral coordination cages and a partial disproportionation into two distinct types of V. The phase does not have a ferromagnetic ground state. The results show that the physics of 1T-VSe2 are richer than previously known with an interplay of Fermi surface instabilities and local bonding effects.

Automated summary

The study reveals the existence of a low-energy metastable phase in monolayer VSe2 with magnetic and electronic properties distinct from the known CDW phase, but very close in energy, likely to be observed in experiments. The results indicate a richer physics of 1T-VSe2 with an interplay of Fermi surface instabilities and local bonding effects.