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

Overview & Synopsis

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 $U \thickapprox$ 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.