Strength of the phonon-coupling mode in $La_{2-x}Sr_{x}CuO_{4}$, $Bi_{2}Sr_{2}CaCu_{2}O_{8+x}$ and $YBa_{2}Cu_{3}O_{6+x}$: An estimation from the ARPES-nodal measurements

TL;DR

This study estimates the strength of electron-phonon coupling in high-temperature cuprate superconductors using ARPES measurements, revealing its significant role in quasiparticle dispersion and mass enhancement across different compounds and doping levels.

Contribution

The paper introduces a systematic method to quantify electron-phonon coupling from ARPES data, distinguishing between mass enhancement and coupling strength in cuprates.

Findings

Electron-phonon coupling parameter λ varies with doping and temperature.

Good agreement between theoretical models and experimental ARPES data.

Identification of the role of electron-phonon interactions in high-Tc superconductivity.

Abstract

Despite the intensive efforts for determining the mechanism that causes high-temperature superconductivity in copper oxide materials, no consensus on the pairing mechanism has been reached. Recent advances in high resolution angle-resolved photoemission spectroscopies have suggested that a sizeable electron-phonon coupling exists as the principal cause for kinks in the dispersion relations (energy versus wave vector) of the electronic states. Here, we report on a systematic study about the influence of the electron-phonon coupling parameter "$\lambda$" in the electronic quasiparticle dispersions along the nodal direction for $La_{2-x}Sr_{x}CuO_{4}$, $Bi_{2}Sr_{2}CaCu_{2}O_{8+x}$ and $YBa_{2}Cu_{3}O_{6+x}$. Information about the dressing of the charge carriers, i.e., on the enhancement of the effective mass and the strength of the coupling mode, is obtained as a function of the doping concentration, temperature, momentum and energy from the kink dispersion in the (0-0)-$(\pi,\pi)$ direction of momentum-space avoiding the complications of the \textit{d-}wave superconducting gap. Our analysis shows a remarkable agreement between theory and experiment for different samples and at different doping levels. This includes our recently introduced theoretical model to adjust the experimental data of the fermionic band dispersion, emphasising the necessary distinction between the general electron mass-enhancement parameter $\lambda^{*}$ and the conventional electron-phonon coupling parameter $\lambda$.