Stacking order and interlayer coupling tuning the properties of charge density waves in layered 1T-NbSe_2

TL;DR

This study uses density functional theory to explore how stacking order and interlayer coupling influence the electronic and magnetic properties of layered 1T-NbSe_2, revealing tunable charge density wave behaviors and magnetic states.

Contribution

It systematically analyzes the effects of stacking configurations and interlayer interactions on the properties of 1T-NbSe_2, a topic less explored in prior research.

Findings

Monolayer 1T-NbSe_2 is a magnetic insulator with 2 lattice modulation.

Magnetic properties of bilayer 1T-NbSe_2 depend on stacking order due to spin charge transfer.

Bulk 1T-NbSe_2 exhibits a 0.02 eV band gap from interlayer spin coupling.

Abstract

Layered transition metal dichalcogenide 1T-NbSe_2 is a good candidate to explore the charge density wave (CDW) and Mott physics. However, the effects of stacking orders and interlayer coupling in CDW 1T-NbSe_2 are still less explored and understood. Using density functional theory calculations, we present a systematic study of the electronic and magnetic properties of monolayer and layered CDW 1T-NbSe_2. Our results indicate that monolayer CDW 1T-NbSe_2 is a magnetic insulator with \sqrt13\times\sqrt13 periodic lattice modulation. Nevertheless, the magnetic properties of bilayer CDWs 1T-NbSe_2 are found stacking orders dependence. The mechanism is understood by the changes of local magnetic moments in each layer due to spin charge transfer between interlayers. Furthermore, the bulk CDW 1T-NbSe_2 opens a band gap with 0.02 eV in 1\times 1 \times 2 supercell due to the interlayer spin coupling. We also discover that the electronic structures of layered 1T-NbSe_2 show a strong dependence on stacking configurations and dimensionality.