Effects of strong correlations on the disorder-induced zero-bias anomaly in the extended Anderson-Hubbard model

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 (EAHM) on a square lattice. The EAHM has both on-site and nearest-neighbour interactions and randomly chosen site energies. We use a mean-field theory that incorporates strong correlations and treats the disorder potential exactly. We use a simplified atomic-limit approximation for the diagonal inelastic self-energy that becomes exact in the large-disorder limit, and 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 ZBA gap when the interaction is finite ranged.