Pressure-Temperature Phase Diagram of Vanadium Dioxide

TL;DR

This study maps the pressure-temperature phase diagram of vanadium dioxide nanobeams, revealing new phases and transition features through combined experimental and computational methods.

Contribution

It provides the first detailed pressure-temperature phase diagram of VO2 nanobeams, identifying new phases and transition boundaries with combined optical, electrical, and density functional analysis.

Findings

Identification of a new insulating M1' phase at high pressure

Discovery of two metallic phases, X and O, with distinct structures

Mapping of phase boundaries and transition features in VO2 nanobeams

Abstract

The complexity of strongly correlated electron physics in vanadium dioxide is exemplified as its rich phase diagrams of all kinds, which in turn shed light on the mechanisms behind its various phase transitions. In this work, we map out the hydrostatic pressure - temperature phase diagram of vanadium dioxide nanobeams by independently varying pressure and temperature with a diamond anvil cell. In addition to the well-known insulating M1 (monoclinic) and metallic R (tetragonal) phases, the diagram identifies the existence at high pressures of the insulating M1' (monoclinic, more conductive than M1) phase, and two metallic phases of X (monoclinic) and O (orthorhombic, at high temperature only). Systematic optical and electrical measurements combined with density functional calculations allow us to delineate their phase boundaries as well as reveal some basic features of the transitions.