Effects of Strong Correlations on the Zero Bias Anomaly in the Extended Hubbard Model with Disorder

TL;DR

This study investigates how strong electronic correlations influence the zero bias anomaly in disordered two-dimensional systems, revealing that correlations significantly modify the Coulomb gap especially at half filling.

Contribution

It introduces a self-consistent dynamical mean field approach with simplified self-energy approximations to analyze the ZBA in the extended Hubbard model with disorder.

Findings

Strong correlations significantly affect the ZBA at half filling.

Finite-range interactions enhance the Coulomb gap.

The approximations used are valid in the large-disorder limit.

Abstract

We study the effect of strong correlations on the zero bias anomaly (ZBA) in disordered interacting systems. We focus on the two-dimensional extended Anderson-Hubbard model, which has both on-site and nearest-neighbor interactions on a square lattice. We use a variation of dynamical mean field theory in which the diagonal self-energy is solved self-consistently at each site on the lattice for each realization of the randomly-distributed disorder potential. Since the ZBA occurs in systems with both strong disorder and strong interactions, we use a simplified atomic-limit approximation for the diagonal inelastic self-energy that becomes exact in the large-disorder limit. The off-diagonal self-energy is treated within the Hartree-Fock approximation. The validity of these approximations is discussed in detail. We find that strong correlations have a significant effect on the ZBA at half filling, and enhance the Coulomb gap when the interaction is finite-ranged.