Non-local Coulomb interactions on the triangular lattice in the high-doping regime: Spectra and charge dynamics from Extended Dynamical Mean Field Theory

TL;DR

This study investigates the effects of non-local Coulomb interactions on the triangular lattice in high doping regimes using Extended Dynamical Mean Field Theory, revealing a metallic phase, symmetry breaking, and unique screening behaviors.

Contribution

It applies Extended Dynamical Mean Field Theory to the extended Hubbard model on a triangular lattice, providing new insights into charge dynamics and spectra at high doping levels.

Findings

Identification of a metallic phase and symmetry-broken phase at strong intersite interactions.

Observation of Hubbard satellites in spectra despite near non-interacting local susceptibilities.

Discovery of a region with negative static local screening.

Abstract

We explore the two-dimensional extended Hubbard model on the triangular lattice in the high doping regime. On-site and nearest-neighbour repulsive interactions are treated in a non-perturbative way by means of Extended Dynamical Mean Field Theory. We compute the low-temperature phase diagram, displaying a metallic phase and a symmetry-broken phase for strong intersite repulsions. We describe the correlation effects on both single-particle and two-particle observables in the metallic phase. Whereas single-particle spectra feature a Hubbard satellite typical of strongly correlated systems, local susceptibilities remain close to their non-interacting limit, even for large on-site repulsions. We argue that this behaviour is typical of the strongly doped case. We also report a region in parameter space with negative static local screening.