Electron-phonon renormalization in small Fermi energy systems

TL;DR

This paper investigates how small Fermi energies, comparable to boson energies, cause deviations in electron-phonon interactions, affecting ARPES data interpretation in cuprates and challenging conventional analysis assumptions.

Contribution

It highlights the failure of standard analysis assumptions in small Fermi energy systems and discusses the resulting novel features in electron self-energy.

Findings

Conventional analysis assumptions break down when Fermi energy is small.

New features in electron self-energy emerge in small Fermi energy regimes.

Implications for interpreting ARPES data in cuprates are discussed.

Abstract

The puzzling features of recent photoemission data in cuprates have been object of several analysis in order to identity the nature of the underlying electron-boson interaction. In this paper we point out that many basilar assumptions of the conventional analysis as expected to fail in small Fermi energy systems when, as the cuprates, the Fermi energy $E_{\rm F}$ is comparable with the boson energy scale. We discuss in details the novel features appearing in the self-energy of small Fermi energy systems and the possible implications on the ARPES data in cuprates.