Magnetic and transport studies of pure ${\mathrm{V}}_2$${\mathrm{O}}_3$ under pressure

We report a systematic study of the resistivity and magnetic susceptibility of pure ${\mathrm{V}}_2$${\mathrm{O}}_3$, the original Mott-Hubbard system at half filling, for pressures 0≤P≤25 kbar and temperatures 0.35≤T≤300 K. We also study (${\mathrm{V}}_{0.99}$${\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$.