Charge Dynamics in Cuprate Superconductors

TL;DR

This paper explores charge carrier dynamics in cuprate superconductors, focusing on charge transfer, Coulomb screening, and collective modes within an extended p-d model, revealing how long-range interactions influence phase separation and lattice properties.

Contribution

It introduces an analysis of charge dynamics considering long-range Coulomb interactions in cuprates, highlighting their effect on phase separation and charge susceptibilities.

Findings

Long-range Coulomb forces frustrate phase separation in cuprates.

Static dielectric function remains negative at small wavevectors without causing instability.

Charge susceptibilities impact lattice properties and collective modes.

Abstract

In this lecture we present some interesting issues that arise when the dynamics of the charge carriers in the CuO$_2$ planes of the high temperature superconductors is considered. Based on the qualitative picture of doping, set by experiments and some previous calculations, we consider the strength of various inter and intra-cell charge transfer susceptibilities, the question of Coulomb screening and charge collective modes. The starting point is the usual p-d model extended by the long range Coulomb (LRC) interaction. Within this model it is possible to examine the case in which the LRC forces frustrate the electronic phase separation, the instability which is present in the model without an LRC interaction. While the static dielectric function in such systems is negative down to arbitrarily small wavevectors, the system is not unstable. We consider the dominant electronic charge susceptibilities and possible consequences for the lattice properties.