Surface effects on the Mott-Hubbard transition in archetypal V$_2$O$_3$

TL;DR

This study investigates how surface crystallography and defects influence the metal-insulator transition in V$_2$O$_3$, revealing surface-dependent domain formation and metallic surface states through combined experimental and theoretical approaches.

Contribution

It provides new insights into surface effects on the Mott-Hubbard transition in V$_2$O$_3$, combining microscopy, diffraction, and advanced theoretical modeling.

Findings

Surface defects act as nucleation centers for metallic domains.

Surface reconstruction with vanadyl cations enhances surface metallicity.

Surface orientation influences domain formation during the transition.

Abstract

We present an experimental and theoretical study exploring surface effects on the evolution of the metal-insulator transition in the model Mott-Hubbard compound Cr-doped V$_2$O$_3$. We find a microscopic domain formation that is clearly affected by the surface crystallographic orientation. Using scanning photoelectron microscopy and X-ray diffraction, we find that surface defects act as nucleation centers for the formation of domains at the temperature-induced isostructural transition and favor the formation of microscopic metallic regions. A density functional theory plus dynamical mean field theory study of different surface terminations shows that the surface reconstruction with excess vanadyl cations leads to doped, and hence more metallic surface states, explaining our experimental observations.