Singular quasiparticle scattering in the proximity of charge instabilities

TL;DR

This paper investigates how quasiparticle scattering behaves near charge instabilities in high-temperature superconductors, revealing strong, anisotropic singularities that significantly influence normal state properties.

Contribution

It demonstrates the nature of singular quasiparticle scattering near charge instabilities using the Hubbard-Holstein model and large-N techniques, highlighting effects of Coulomb forces.

Findings

Scattering amplitude is strongly singular near phase separation without Coulomb forces.

Charge instability occurs at finite wavevectors with Coulomb forces, maintaining strong anisotropic scattering.

Normal state properties are significantly affected by this singular scattering.

Abstract

We analyze the behavior of the dynamic scattering amplitude between Fermi liquid quasiparticles at the Fermi surface in the proximity of a charge instability, which may occur in the high temperature superconducting cuprates. Within the infinite-U Hubbard-Holstein model in the slave-boson large-N technique we find that, in the absence of long-range Coulomb forces the scattering amplitude is strongly singular at zero momentum transfer close to the phase separation instability and it has the same form provided by gauge-field theories. In the presence of long-range Coulomb forces the charge instability occurs at finite wavevectors and concomitantly the scattering is still singular but anisotropic. Nevertheless it remains strong over extended regions of the momentum space. In both cases we show how normal state properties are largely affected by this scattering.