Theory for the excitation spectrum of High-T$_c superconductors : quasiparticle dispersion and shadows of the Fermi surface

TL;DR

This paper introduces a new method to analyze the excitation spectrum of high-temperature superconductors, revealing how magnetic order influences quasiparticle behavior and Fermi surface features, with implications for photoemission experiments.

Contribution

A novel solution to FLEX equations for the 2D Hubbard model on the real frequency axis, providing new insights into quasiparticle dispersion and Fermi surface shadows in high-Tc superconductors.

Findings

Revealed doping dependence of quasiparticle excitations

Identified anomalous ω-dependence of ImΣ_k(ω)

Observed violation of Luttinger theorem

Abstract

Using a new method for the solution of the FLEX-equations, which allows the determination of the self energy $\Sigma_{\bf k}(\omega)$ of the $2D$ Hubbard model on the real frequency axis, we calculate the doping dependence of the quasi-particle excitations of High-T$_c$ superconductors. We obtain new results for the shadows of the Fermi surface, their dependence on the deformation of the quasi particle dispersion, an anomalous $\omega$-dependence of ${\rm Im}\Sigma_{\bf k}(\omega)$ and a related violation of the Luttinger theorem. This sheds new light on the influence of short range magnetic order on the low energy excitations and its significance for photoemission experiments.