Three-orbital continuous model for $1H$-type metallic transition-metal dichalcogenide monolayers

TL;DR

This paper develops a new three-orbital continuous model for metallic 1H-type transition-metal dichalcogenide monolayers, accurately capturing electronic states near Fermi pockets and highlighting the importance of chalcogen p orbitals.

Contribution

It introduces a first-principles-based 3x3 Hamiltonian model that improves upon conventional models by including chalcogen p orbitals for metallic TMDCs.

Findings

The model accurately reproduces electronic states around Fermi pockets.

Chalcogen p orbitals are crucial for metallic TMDC electronic structure.

The model describes Berry curvature and transport phenomena effectively.

Abstract

We theoretically investigate the electronic states in monolayer NbSe$_2$ and develop continuous models to describe these states in Fermi pockets. In $1H$-type metallic transition-metal dichalcogenides(TMDCs), the Femi surface consists of three pockets enclosing the $\Gamma$, $K$, and $K'$ points. We reveal that the conventional effective model used for semiconducting TMDCs is not sufficient to describe the electronic states in metallic TMDCs and thus introduce a scheme to construct the effective model from the first-principles results. All models can be represented by $3\times3$ Hamiltonian and well reproduce electronic states around the Fermi energy in terms of the orbital composition and the phase factor. We also show that the $p$ orbitals in chalcogen atoms, which are ignored in the conventional $2\times2$ model, play a crucial role in metallic TMDCs. Although the aim of these models is to reproduce electronic states, they can well describe states near the high-symmetry points and the profile of Berry curvature in the wave vector space. The continuous model can be a handleable tool to describe the electronic states and to analyze the transport phenomena in metallic TMDCs.