Optical properties ofV2O3in its whole phase diagram

Abstract

Vanadium sesquioxide ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ is considered a textbook example of Mott-Hubbard physics. In this paper, we present an extended optical study of its whole temperature/doping phase diagram as obtained by doping the pure material with $M=\text{Cr}$ or Ti atoms $({\mathrm{V}}_{1\ensuremath{-}x}\phantom{\rule{0.16em}{0ex}}{M}_{x}){}_{2}{\mathrm{O}}_{3}$. We reveal that its thermodynamically stable metallic and insulating phases, although macroscopically equivalent, show very different low-energy electrodynamics. The Cr and Ti doping drastically change both the antiferromagnetic gap and the paramagnetic metallic properties. A slight chromium content induces a mesoscopic electronic phase separation, while the pure compound is characterized by short-lived quasiparticles at high temperature. This study thus provides a new comprehensive scenario of the Mott-Hubbard physics in the prototype compound ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$.