Electron self-energy from quantum charge fluctuations in the layered t-J model with long-range Coulomb interaction

TL;DR

This paper investigates how quantum charge fluctuations influence the electron self-energy in a layered t-J model with long-range Coulomb interactions, revealing asymmetries, spectral changes, and the dominance of high-energy charge excitations.

Contribution

It introduces a large-N scheme to analyze charge fluctuation effects on electron self-energy in the layered t-J model, highlighting the roles of on-site and bond-charge fluctuations.

Findings

Pronounced asymmetry in ImΣ(k,ω) driven by strong correlations

Significant reduction of quasiparticle weight along the Fermi surface

Emergence of incoherent and side bands with sizable spectral weight

Abstract

Employing a large-N scheme of the layered t-J model with the long-range Coulomb interaction, which captures fine details of the charge excitation spectra recently observed in cuprate superconductors, we explore the role of the charge fluctuations on the electron self-energy. We fix temperature at zero and focus on quantum charge fluctuations. We find a pronounced asymmetry of the imaginary part of the self-energy Im$\Sigma({\bf k}, \omega)$ with respect to $\omega = 0$, which is driven by strong electron correlation effects. The quasiparticle weight is reduced dramatically, which occurs almost isotropically along the Fermi surface. Concomitantly an incoherent band and a sharp side band are newly generated and acquire sizable spectral weight. All these features are driven by usual on-site charge fluctuations, which are realized in a rather high-energy region and yield plasmon excitations. On the other hand, the low-energy region with the scale of the superexchange interaction J is dominated by bond-charge fluctuations. Surprisingly, compared with the effect of the on-site charge fluctuations, their effect on the electron self-energy is much weaker even if the system approaches close to bond-charge instabilities. Furthermore, quantum charge dynamics does not produce a clear kink nor a pseudogap in the electron dispersion.