Resolving the VO$_2$ controversy: Mott mechanism dominates the insulator-to-metal transition

TL;DR

This study uses a Hubbard model and Dynamical Mean Field Theory to demonstrate that the insulator-to-metal transition in VO$_2$ is primarily driven by a Mott electronic mechanism, aligning well with experimental data.

Contribution

It provides the first detailed theoretical evidence that the VO$_2$ transition is dominated by Mott physics, resolving a long-standing controversy.

Findings

Good agreement with experimental optical conductivity data

Identification of a novel metallic state with split heavy quasiparticle band

Confirmation that the transition is Mott-driven rather than Peierls-based

Abstract

We consider a minimal model to investigate the metal-insulator transition in VO$_2$. We adopt a Hubbard model with two orbital per unit cell, which captures the competition between Mott and singlet-dimer localization. We solve the model within Dynamical Mean Field Theory, characterizing in detail the metal-insulator transition and finding new features in the electronic states. We compare our results with available experimental data obtaining good agreement in the relevant model parameter range. Crucially, we can account for puzzling optical conductivity data obtained within the hysteresis region, which we associate to a novel metallic state characterized by a split heavy quasiparticle band. Our results show that the thermal-driven insulator-to-metal transition in VO$_2$ is compatible with a Mott electronic mechanism, providing fresh insight to a long standing "chicken-and-egg" debate and calling for further research of "Mottronics" applications of this system.