Charged excitons in doped extended Hubbard model systems

TL;DR

This paper demonstrates that charge transfer excitons in doped Hubbard models with extended Coulomb interactions significantly influence spectroscopic features, revealing new satellite structures and spectral weight dependencies on doping and dimensionality.

Contribution

It introduces the impact of longer-range Coulomb interactions on excitonic features and spectral properties in doped Hubbard models, highlighting differences from simple models.

Findings

Charge transfer excitons attain charge in doped systems.

Satellites appear in spectra due to extended Coulomb interactions.

Spectral weight of satellites depends on doping and dimensionality.

Abstract

We show that the charge transfer excitons in a Hubbard model system including nearest neighbor Coulomb interactions effectively attain some charge in doped systems and become visible in photoelectron and inverse photoelectron spectroscopies. This shows that the description of a doped system by an extended Hubbard model differs substantially from that of a simple Hubbard model. Longer range Coulomb interactions cause satellites in the one electron removal and addition spectra and the appearance of spectral weight if the gap of doped systems at energies corresponding to the excitons of the undoped systems. The spectral weight of the satellites is proportional to the doping times the coordination number and therefore is strongly dependent on the dimension.