Structural precursor to the metal-insulator transition in V_2O_3

TL;DR

This study reveals that in V_2O_3, structural changes along the c-axis occur abruptly at the metal-insulator transition, while in-plane tilts develop gradually, highlighting the importance of electron-lattice interactions and orbital effects in driving the transition.

Contribution

It provides experimental evidence linking local structural distortions to the metal-insulator transition, emphasizing the role of in-plane interactions and orbital hybridization.

Findings

Vanadium pair distance changes abruptly at MIT

In-plane tilt increases gradually before MIT

Electron-lattice coupling influences the transition

Abstract

The temperature dependence of the local structure of V_2O_3 in the vicinity of the metal to insulator transition (MIT) has been investigated using hard X-ray absorption spectroscopy. It is shown that the vanadium pair distance along the hexagonal c-axis changes abruptly at the MIT as expected. However, a continuous increase of the tilt of these pairs sets in already at higher temperatures and reaches its maximum value at the onset of the electronic and magnetic transition. These findings confirm recent theoretical results which claim that electron-lattice coupling is important for the MIT in V_2O_3. Our results suggest that interactions in the basal plane play a decisive role for the MIT and orbital degrees of freedom drive the MIT via changes in hybridization.