An unconventional Fermi liquid model for the optimally doped and overdoped cuprate superconductors

Abstract

Based on an unconventional Fermi liquid model, we present several results on the optimally doped and overdoped cuprate superconductors. For the normal state, we provide an analytic demonstration, backed by self-consistent Baym-Kadanoff (BK) numerical calculations, of the linear in $T$ resistivity and linear in 1/$ε$ optical conductivity, provided the interacting Fermi liquid has strong peaks in its density of states (van-Hove singularities in 2 dimensions) near the chemical potential $μ$. Moreover, we find that the interactions tend to pin these strong density of states peaks close to $μ$. We show that the low energy dependence of $χ_{MMP}$ has a fermionic origin. We obtain particularly high transition temperatures $T_c$ from our BK-Eliashberg scheme by introducing an ansatz for the fermionic susceptibility of the carriers. We postulate that the latter is enhanced in an additive manner due to the weak antiferromagnetic order of the CuO$_2$ planes. We have obtained a $d_{x^2-y^2}$ gap with $T_c > 120 ^o$K for n.n. hopping $t=250meV$.