On the charge and magnetic ordering in monolayer NbSe$_2$: a first principles study

TL;DR

This study uses first principles calculations to explore charge and magnetic orders in monolayer NbSe$_2$, revealing magnetic instability, competing charge-density wave structures, and their relation to superconductivity.

Contribution

It uncovers the magnetic instability and identifies two competing charge-density wave structures in monolayer NbSe$_2$, linking them to its superconducting properties.

Findings

Magnetic instability in pristine monolayer NbSe$_2$ due to reduced screening.

Identification of two distinct $3 imes3$ charge-density wave structures.

Significant impact of CDW phases on the Fermi surface and superconductivity.

Abstract

Monolayer NbSe$_2$ has recently been shown to be a 2-dimensional superconductor, with a competing charge-density wave (CDW) order. This work investigates the electronic structure of monolayer NbSe$_2$ based on first principles calculations, focusing on charge and magnetic orders in connection to the superconductivity. It is found that decreased screening in the monolayer NbSe$_2$ with a perfect lattice exhibits magnetic instability, which is removed by the formation of CDW. Two energetically competitive but distinct $3\times3$ CDW structures are revealed computationally, which have a significant impact on the Fermi surface. The relations of the potential CDW phases with experimental structure and the coexisting superconductivity are discussed.