Raman spectrum and charge fluctuations in the copper-oxide superconductors

TL;DR

This paper investigates how charge fluctuations influence the electronic and Raman spectra of high-temperature superconductors using a non-crossing approximation within the slave boson framework, aligning theoretical results with experimental observations.

Contribution

It introduces a non-crossing approximation approach to study charge fluctuations in high-Tc superconductors, improving upon saddle point methods.

Findings

Electronic Raman spectrum is featureless up to a certain frequency.

Dependence on light polarization matches experimental data.

Renormalized hole spectrum and lifetime are calculated accurately.

Abstract

The effect of the charge fluctuations on the electronic spectrum and the Raman spectrum of high temperature superconductors is examined within the slave boson approach. Instead of using the saddle point approximation for slave bosons, we confine ourselves to the non-crossing approximation (NCA) in summing the diagrams for the Green functions, thus obtaining the renormalized hole spectrum and its lifetime on equal footing. The electronic Raman spectrum is calculated, showing the characteristic featureless behaviour up to the frequency of the order of renormalized $\Delta_{pd}$ parameter. The dependence on the polarization of the incident and the scattered light agrees with experiments.