Soft-x-ray photoemission study of the electronic structure of ${\mathrm{Bi}}_4{\mathrm{Ca}}_3{\mathrm{Sr}}_3{\mathrm{Cu}}_4{\mathrm{O}}_{16+x}$

We investigated the electronic structure of the high-temperature superconductor ${\mathrm{Bi}}_4{\mathrm{Ca}}_3{\mathrm{Sr}}_3{\mathrm{Cu}}_4{\mathrm{O}}_{16+x}$ with synchrotron-radiation photoemission spectroscopy. This study complements recent experiments focused on the Fermi-edge region, which discovered substantial line-shape changes related to the onset of superconductivity. In the present case, spectra taken at different photon energies exhibit a variety of features related to core and valence electrons. In particular, we exploit the photon energy tunability of the source of identify the valence Cu satellite with resonant photoemission.