Charge instabilities of the extended attractive Hubbard Model on the cubic lattice

TL;DR

This study investigates charge instabilities in the extended attractive Hubbard model on a cubic lattice, revealing how non-local interactions influence the stability of the Fermi liquid phase and the emergence of charge order.

Contribution

It provides a detailed analysis of charge instabilities and the Brinkman-Rice transition within the extended attractive Hubbard model using the Kotliar-Ruckenstein slave-boson approach.

Findings

Quasiparticle residue vanishes near Uc, indicating a Brinkman-Rice transition.

Charge instabilities occur in a narrow density window around quarter filling for certain interactions.

Attractive non-local interactions expand the parameter space where charge instabilities are observed.

Abstract

The paramagnetic phase of the extended attractive Hubbard model on the cubic lattice is studied within the spin rotation invariant Kotliar-Ruckenstein slave-boson representation at zero temperature. It is obtained that the quasiparticle residue of the Fermi liquid phase vanishes for all densities at an interaction strength slightly smaller than $U_c$ that signals the Brinkman-Rice transition, and that it weakly depends on density. While for vanishing non-local interaction parameters homogeneous static charge instabilities are found in a rather narrow window centered around quarter filling and $U \simeq 0.8\ U_c$, increasing them to $V = -0.2\ U$ results into a severe narrowing of this window. On the contrary, when all interaction parameters are attractive, for example for $V = 0.2\ U$, a large parameter range in which homogeneous static charge instabilities is found. Yet, this systematically happens inside the Fermi liquid phase.