Observation of a robust peak in the glue function of the high-Tc cuprates in the 50-60 meV range

TL;DR

This study reconstructs the glue function in high-Tc cuprates using optical conductivity data, revealing a consistent peak at 50-60 meV and a broad continuum, with a correlation to the critical temperature.

Contribution

It introduces a method to extract the glue spectrum from optical conductivity, uncovering a universal peak in high-Tc cuprates across various doping levels and temperatures.

Findings

Robust peak at 50-60 meV in the glue function

Broad continuum at higher energies

Correlation between glue spectrum and critical temperature

Abstract

We take advantage of the connection between the free carrier optical conductivity and the glue function in the normal state, to reconstruct from the infrared optical conductivity the glue-spectrum of ten different high-Tc cuprates revealing a robust peak in the 50-60 meV range and a broad continuum at higher energies for all measured charge carrier concentrations and temperatures up to 290 K. We observe an intriguing correlation between the doping trend of the experimental glue spectra and the critical temperature.