  Vanadium sesquioxide, V2O3, is a prototypical metal-to-insulator system
where, in temperature-dependent studies, the transition always coincides with a
corundum-to-monoclinic structural transition. As a function of pressure, V2O3
follows the expected behavior of increased metallicity due to a larger
bandwidth for pressures up to 12.5 GPa. Surprisingly, for higher pressures when
the structure becomes unstable, the resistance starts to increase. Around 32.5
GPa at 300 K, we observe a novel pressure-induced corundum-to-monoclinic
transition between two metallic phases, showing that the structural phase
transition can be decoupled from the metal-insulator transition. Using X-ray
Raman scattering, we find that screening effects, which are strong in the
corundum phase, become weakened at high pressures. Theoretical calculations
indicate that this can be related to a decrease in coherent quasiparticle
strength, suggesting that the high-pressure phase is likely a critical
correlated metal, on the verge of Mott-insulating behavior.
