Apparent electron-phonon interaction in strongly correlated systems

TL;DR

This paper investigates how electron-phonon interactions manifest differently in strongly correlated systems like high-T_c cuprates, revealing that observed effects depend on the property measured and doping levels.

Contribution

It demonstrates that the apparent electron-phonon coupling varies with the property studied and doping, clarifying experimental interpretations in strongly correlated materials.

Findings

Phonon self-energy effects are reduced by doping level delta.

Electron self-energy coupling remains unaffected by doping.

Supports interpretation of photoemission experiments indicating strong electron-phonon coupling.

Abstract

We study the interaction of electrons with phonons in strongly correlated solids, having high-T_c cuprates in mind. Using sum-rules, we show that the apparent strength of this interaction strongly depends on the property studied. If the solid has a small fraction (doping) delta of charge carriers, the influence of the interaction on the phonon self-energy is reduced by a factor delta, while there is no corresponding reduction of the coupling seen in the electron self-energy. This supports the interpretation of recent photoemission experiments, assuming a strong coupling to phonons.