Quantitative Determination of Eliashberg Function and Evidence of Strong Electron Coupling with Multiple Phonon Modes in Heavily Over doped (Bi,Pb)2Sr2CuO6

TL;DR

This study uses high-resolution laser ARPES to quantitatively analyze the Eliashberg function in heavily overdoped cuprates, revealing strong electron-phonon coupling with multiple phonon modes.

Contribution

It introduces a general procedure to determine the bare band and extract the bosonic spectral function from high-precision ARPES data.

Findings

70 meV nodal kink caused by electron coupling with multiple phonon modes

Large mass enhancement factor λ= 0.42 in heavily overdoped regime

Unambiguous evidence of strong electron-phonon coupling

Abstract

Super-high resolution laser-based angle-resolved photoemission spectroscopy measurements have been carried out on a heavily overdoped (Bi,Pb)2Sr2CuO6 (Tc> 5 K) superconductor. Taking advantage of the high-precision data on the subtle change of the quasi-particle dispersion at different temperatures, we develop a general procedure to determine the bare band dispersion and extract the bosonic spectral function quantitatively. Our results show unambiguously that the 70 meV nodal kink is due to the electron coupling with the multiple phonon modes, with a large mass enhancement factor Lamda= 0.42 even in the heavily over-doped regime.