Magnetic and transport studies of pure V2O3 under pressure.

Abstract

We report a systematic study of the resistivity and magnetic susceptibility of pure ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$, the original Mott-Hubbard system at half filling, for pressures 0\ensuremath{\le}P\ensuremath{\le}25 kbar and temperatures 0.35\ensuremath{\le}T\ensuremath{\le}300 K. We also study (${\mathrm{V}}_{0.99}$${\mathrm{Ti}}_{0.01}$${)}_{2}$${\mathrm{O}}_{3}$ under pressure in order to elucidate the role of disorder on a metal-insulator transition in the highly correlated limit. Despite the low level of doping, we find that the two systems are very different. We observe a conventional collapsing of the Mott-Hubbard gap only for stoichiometric ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$; the Ti disorder stabilizes the long-range antiferromagnetic order and a magnetic Slater gap. Moreover, we discover different P-T phase diagrams for the two systems, with a decoupling of the charge and spin degrees of freedom at the approach to the T=0, pressure-driven metal-insulator transition in pure ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$.