Pressure-induced superconductivity in β-Na0.33V2O5 beyond charge ordering -: art. no. 057002

We report the discovery of a new superconducting phase in highly correlated 3d electron systems. The compound is beta-vanadium bronze, beta-Na0.33V2O5, in which the charge-ordered phase collapses under hydrostatic high pressure and a pressure-induced superconducting phase appears around T-SC=8 K, P=8 GPa. This report presents the first observation not only of superconductivity in vanadium oxides but also of a phase transition from charge ordered to superconducting on a pressure-temperature (P-T) plane. The phase diagrams seem to have universal aspects across the classes of materials. This indicates a profound physics of superconductivity in highly correlated electron systems.