Correlating the Energetics and Atomic Motions of the Metal-Insulator Transition of M1 Vanadium Dioxide

TL;DR

This study combines first principles calculations and high-resolution X-ray diffraction to elucidate the atomic motions and energy landscape underlying the metal-insulator transition in vanadium dioxide, revealing the microscopic mechanisms involved.

Contribution

It provides a detailed atomic-level understanding of the energy barrier and atomic motions during the transition, advancing the microscopic insight into VO2's phase change.

Findings

Identified an energy barrier involving V-V atomic distance changes.

Observed anisotropic strain broadening in low-temperature structure.

GW calculations show destabilization of bonding/anti-bonding splitting during transition.

Abstract

Materials that undergo reversible metal-insulator transitions are obvious candidates for new generations of devices. For such potential to be realised, the underlying microscopic mechanisms of such transitions must be fully determined. In this work we probe the correlation between the energy landscape and electronic structure of the metal-insulator transition of vanadium dioxide and the atomic motions occurring using first principles calculations and high resolution X-ray diffraction. Calculations find an energy barrier between the high and low temperature phases corresponding to contraction followed by expansion of the distances between vanadium atoms on neighbouring sub-lattices. X-ray diffraction reveals anisotropic strain broadening in the low temperature structure's crystal planes, however only for those with spacings affected by this compression/expansion. GW calculations reveal that traversing this barrier destabilises the bonding/anti-bonding splitting of the low temperature phase. This precise atomic description of the origin of the energy barrier separating the two structures will facilitate more precise control over the transition characteristics for new applications and devices.