Real space investigation of structural changes at the metal-insulator transition in VO2

TL;DR

This study uses synchrotron X-ray total scattering to investigate structural changes in VO2 at its metal-insulator transition, revealing phase coexistence and detailed local structural behavior without intermediate phases.

Contribution

It provides the first detailed local structure analysis of VO2's phase transition, confirming phase coexistence and high correlation in the low-temperature phase.

Findings

Monoclinic and tetragonal phases coexist at transition temperature

No evidence of intermediate phases during transition

High correlation in the low-temperature dimerized structure

Abstract

Synchrotron X-ray total scattering studies of structural changes in rutile VO2 at the metal-insulator transition temperature of 340 K reveal that monoclinic and tetragonal phases of VO2 coexist in equilibrium, as expected for a first-order phase transition. No evidence for any distinct intermediate phase is seen. Unbiased local structure studies of the changes in V--V distances through the phase transition, using reverse Monte Carlo methods, support the idea of phase coexistence and point to the high degree of correlation in the dimerized low-temperature structure. No evidence for short range V--V correlations that would be suggestive of local dimers is found in the metallic phase.