Phonon origin of low energy and high energy kinks in high temperature cuprate superconductors

TL;DR

This paper uses an extended Eliashberg theory to demonstrate that phonons can explain both low-energy and high-energy kinks observed in the electron Green function of high-temperature cuprate superconductors, aligning with experimental data.

Contribution

It introduces a generalized Eliashberg framework accounting for electron-hole asymmetry and correlations to explain spectral kinks in cuprates.

Findings

Both low-energy and high-energy kinks are reproduced by phonon interactions.

The theory explains the abnormal band broadening near optimal doping.

Results align with experimental observations of spectral features in cuprates.

Abstract

Eliashberg theory generalized for the account of the electron-hole nonequivalence and electron correlations in the vertex function is used. The phonon contribution to the nodal electron Green function in cuprates is viewed. At non- zero temperatures the singularities (kinks) in the frequency behavior of a real and imaginary part of an electron nodal Green function, and also in the nodal part of the density of the electron states modified by an electron-phonon interaction are studied. It is shown that near the optimal doping both the low-energy and high-energy nodal Green function kinks and also the abnormal broadening of a band in cuprates are reproduced with the electron-phonon interaction in the extended Eliashberg theory.