Direct Observation of Decoupled Structural and Electronic Transitions and an Ambient Pressure Monoclinic-Like Metallic Phase of VO$_2$

TL;DR

This study reveals that VO$_2$ undergoes separate structural and electronic transitions, with a unique monoclinic-like metallic phase at ambient pressure, challenging previous assumptions about its metal-insulator transition.

Contribution

It provides the first direct observation of a monoclinic-like metallic phase at ambient pressure, demonstrating the decoupling of structural and electronic transitions in VO$_2$.

Findings

Structural and electronic transitions occur at different temperatures.

Identification of a monoclinic-like metallic phase at ambient pressure.

Implications for the understanding of VO$_2$'s metal-insulator transition.

Abstract

We report the simultaneous measurement of the structural and electronic components of the metal-insulator transition of VO$_2$ using electron and photoelectron spectroscopies and microscopies. We show that these evolve over different temperature scales, and are separated by an unusual monoclinic-like metallic phase. Our results provide conclusive evidence that the new monoclinic-like metallic phase, recently identified in high-pressure and nonequilibrium measurements, is accessible in the thermodynamic transition at ambient pressure, and we discuss the implications of these observations on the nature of the MIT in VO$_2$.