Bare electron dispersion from experiment: Self-consistent self-energy analysis of photoemission data

Abstract

Performing an in-depth analysis of the photoemission spectra along the nodal direction of the high-temperature superconductor Bi-2212 we developed a procedure to determine the underlying electronic structure and established a precise relation of the measured quantities to the real and imaginary parts of the self-energy of electronic excitations. The self-consistency of the procedure with respect to the Kramers-Kronig transformation allows us to draw conclusions on the applicability of the spectral function analysis and on the existence of well-defined quasiparticles along the nodal direction even for the underdoped Bi-2212 in the pseudogap state. The analysis of the real part of the self-energy ${\ensuremath{\Sigma}}^{\ensuremath{'}}(\ensuremath{\omega})$ for an overdoped and underdoped Bi-2212 helps to distinguish the $70\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ ``kink'' from ${\ensuremath{\Sigma}}^{\ensuremath{'}}(\ensuremath{\omega})$ maximum and conclude about doping dependence of the kink strength.