Evolution from charge-ordered phase to high-temperature superconductivity

High-temperature superconductivity is achieved through doping Mott insulators, but the critical process underlying the emergence of superconductivity remains unclear, especially when electron-electron correlations dominate. Using high-resolution resonant inelastic X-ray scattering (RIXS), we have investigated the evolution of charge orders and phonons in Bi-based cuprates near the onset of the superconducting dome. Our results suggest that Cooper pairs grow out of a pre-existing charge-ordered insulating state and then condense, accompanied by an enhanced interplay between charge excitations and electron-phonon coupling.