Effect of short-range correlations on spectral properties of doped Mott insulators

TL;DR

This study uses cluster perturbation theory to explore how short-range correlations influence the spectral features of doped Mott insulators, revealing phenomena like Fermi pockets and kinks without extra order parameters.

Contribution

It demonstrates that intrinsic short-range correlations can produce complex spectral features in doped Mott insulators, aligning with experimental observations without additional assumptions.

Findings

Reproduces Fermi pockets and arcs in the spectral function.

Shows electron-phonon interactions induce low-energy kinks.

Highlights the role of short-range correlations in spectral anomalies.

Abstract

In the framework of cluster perturbation theory for the 2D Hubbard and Hubbard-Holstein models at low hole doping we have studied the effect of local and short-range correlations in strongly correlated systems on the anomalous features in the electronic spectrum by investigating the fine structure of quasiparticle bands. Different anomalous features of spectrum are obtained as the result of intrinsic properties of strongly correlated electron and polaron bands in the presence of short-range correlations. Particularly, features similar to the electron-like Fermi-pockets of cuprates at hole doping $p\sim0.1$ are obtained without ad hoc introducing a charge density wave order parameter within the Hubbard model in a unified manner with other known peculiarities of the pseudogap phase like Fermi-arcs, pockets, waterfalls, and kink-like features. The Fermi surface is mainly formed by dispersive quasiparticle bands with large spectral weight, formed by coherent low-energy exications. Within the Hubbard-Holstein model at moderate phonon frequencies we show that modest values of local electron-phonon interaction are capable of introducing low-energy kink-like features and affecting the Fermi surface by hybridization of the fermionic quasiparticle bands with the Franck-Condon resonances.