MAGNETIC AND TRANSPORT STUDIES OF PURE V2O3 UNDER PRESSURE

We report a systematic study of the resistivity and magnetic susceptib ility of pure V2O3, the original Mott-Hubbard system at half filling, for pressures 0 less-than-or-equal-to P less-than-or-equal-to 25 kbar and temperatures 0.35 less-than-or-equal-to T less-than-or-equal-to 30 0 K. We also study (V0.99Ti0.01)2O3 under pressure in order to elucida te the role of disorder on a metal-insulator transition in the highly correlated limit. Despite the low level of doping, we find that the tw o systems are very different. We observe a conventional collapsing of the Mott-Hubbard gap only for stoichiometric V2O3; the Ti disorder sta bilizes the long-range antiferromagnetic order and a magnetic Slater g ap. Moreover, we discover different P-T phase diagrams for the two sys tems, with a decoupling of the charge and spin degrees of freedom at t he approach to the T = 0, pressure-driven metal-insulator transition i n pure V2O3.