Angle-resolved photoemission in doped charge-transfer Mott insulators

A theory of angle-resolved photoemission (ARPES) in doped cuprates and other charge-transfer Mott insulators is developed taking into account the realistic (LDA+U) band structure, (bi)polaron formation due to the strong electron-phonon interaction, and a random-field potential. In most of these materials, the first band to be doped is the oxygen band inside the Mott-Hubbard gap. We derive the coherent part of the ARPES spectra with the oxygen hole spectral function calculated in the noncrossing (ladder) approximation and with the exact spectral function of a one-dimensional hole in a random potential. Some unusual features of ARPES, including the polarization dependence and spectral shape in ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_7$ and ${\mathrm{YBa}}_2{\mathrm{Cu}}_4{\mathrm{O}}_8,$ are described without any Fermi surface, large or small. The theory is compatible with the doping dependence of kinetic and thermodynamic properties of cuprates as well as with the d-wave symmetry of the superconducting order parameter.