Unmasking the Origin of Kinks in the Photoemission Spectra of Cuprate Superconductors

TL;DR

This paper uses ab initio calculations to show that correlation-enhanced electron-phonon interactions cause the characteristic kinks in cuprate superconductor spectra, clarifying their origin and doping dependence.

Contribution

It provides a quantitative ab initio explanation for the spectral kinks in cuprates, emphasizing the role of electron density-of-states over mode-coupling strength.

Findings

Correlation-enhanced electron-phonon interaction causes the spectral kinks.

Doping dependence of the kink size is mainly due to electron density-of-states.

Multi-band effects are crucial in understanding the kink phenomena.

Abstract

The origin of a ubiquitous bosonic coupling feature in the photoemission spectra of high-Tc cuprates, an energy-momentum dispersion 'kink' observed at ~70 meV binding energy, remains a two-decade-old mystery. Understanding this phenomenon requires an accurate description of the coupling between the electron and some collective modes. We report here ab initio calculations based on GW perturbation theory and show that correlation-enhanced electron-phonon interaction in cuprates gives rise to the strong kinks, which not only explains quantitatively the observations but provides new understanding of experiments. Our results reveal it is the electron density-of-states being the predominant factor in determining the doping-dependence of the kink size, manifesting the multi-band nature of the cuprates, as opposed to the prevalent belief of it being a measure of the mode-coupling strength.