Electronic structure of tungsten-doped vanadium dioxide

TL;DR

This study uses advanced GW calculations to explore how tungsten doping affects the electronic structure of VO₂, revealing a transition from band insulator to Mott insulator due to doping and defects.

Contribution

The paper provides the first theoretical evidence, using GW methods with local k-space interactions, that tungsten doping induces a Mott-insulating state in VO₂.

Findings

Doping and defects lead to a transition from band to Mott insulator.

Strong correlations are key to maintaining the insulating gap.

GW calculations reveal changes in the electronic structure due to tungsten doping.

Abstract

A common method of adjusting the metal-insulator transition temperature of M$_{1}$ VO$_{2}$ is via disruption of the Peierls pairing by doping, or inputting stress or strain. However, since adding even small amounts of dopants will change the band structure, it is unclear how doped VO$_{2}$ retains its insulating character observed in experiments. While strong correlations may be responsible for maintaining a gap, theoretical evidence for this has been very difficult to obtain due to the complexity of the many-body problem involved. In this work we use GW calculations modified to include strong local $\textbf{k}$-space interactions to investigate the changes in band structure from tungsten doping. We find that the combination of carrier doping and the experimentally observed structural defects introduced by inclusion of tungsten are consistent with a change from band-like to Mott-insulating behavior.