Correlation between Inhomogeneity and Superconductivity in Cuprate Bi₂Sr₂CaCu₂O_8+d at High Pressure

We report a discovery of the correlation between inhomogeneity and superconductivity in single-crystal Bi₂Sr₂CaCu₂O_8+d (Bi-2212) at high pressure, by using multiple synchrotron x-ray techniques. Our imaging and small-angle scattering measurements reveal a newly discovered ribbon phase as well as short-range charge ordering at nano and micron scales. We observe that both pressure and x-ray irradiation could alter the inhomogeneity, and the changes of the ribbon phase’s morphology coincide with the doom-shaped T_C at high pressure. Our x-ray absorption, inelastic scattering, irradiation experiments imply that the inhomogeneity could be associated with an inhomogeneous distribution of oxygen holes. These findings provide a direct link between T_C and inhomogeneity in cuprate Bi-2212 HTSC.