Extracting the spectral function of the cuprates by a full two-dimensional analysis: Angle-resolved photoemission spectra of Bi₂Sr₂CuO₆

Recently, angle-resolved photoemission spectroscopy (ARPES) has revealed a dispersion anomaly at high binding energy near 0.3–0.5 eV in various families of the high-temperature superconductors. For further studies of this anomaly, we present a new two-dimensional fitting scheme and apply it to high-statistics ARPES data of the strongly overdoped Bi₂Sr₂CuO₆ cuprate superconductor. The procedure allows us to extract the self-energy in an extended energy and momentum range. It is found that the spectral function of Bi₂Sr₂CuO₆ can be parametrized using a small set of tight-binding parameters and a weakly momentum-dependent self-energy up to 0.7 eV in binding energy and over the entire first Brillouin zone. Moreover, the analysis gives an estimate of the momentum dependence of the matrix element, a quantity, which is often neglected in ARPES analyses.