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

TL;DR

This paper shows that charge-density-wave formation in monolayer 1T-VSe2 can occur through purely electronic interactions, with Fermi surface nesting playing a key role, and explores the competition with superconductivity.

Contribution

It provides a theoretical analysis demonstrating that CDW can be driven solely by electronic mechanisms in monolayer VSe2, highlighting the importance of Fermi surface nesting and exchange interactions.

Findings

Charge-density-wave order occurs when Heisenberg exchange is comparable to Coulomb repulsion.

$d$-wave superconductivity emerges with purely repulsive interactions.

Lattice vibrations may enhance the effective Heisenberg exchange.

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.