Can Fermi surface nesting alone drive the charge-density-wave transition in monolayer vanadium diselenide?

Abstract: We demonstrate that charge-density-wave formation is possible via a purely electronic mechanism in monolayers of the transition metal dichalcogenide 1T-VSe$_2$. Via a renormalization group treatment of an extended Hubbard model we examine the competition of superconducting and density-wave fluctuations as sections of the Fermi surface are tuned to perfect nesting. We find regions of charge-density-wave order when the Heisenberg exchange interaction is comparable to the Coulomb repulsion, and $d$-wave superconductivity for purely repulsive interactions. We discuss the possible role of lattice vibrations in enhancing the effective Heisenberg exchange.