Doping Evolution of Nodal Band Renormalization in Bi2Sr2CuO6+d Superconductor Revealed by Laser-Based Angle-Resolved Photoemission Spectroscopy

TL;DR

This study uses laser-based ARPES to analyze how nodal band renormalization evolves with doping in Bi2Sr2CuO6+d, revealing two energy scales linked to electron-phonon interactions that influence superconductivity.

Contribution

It provides detailed doping and temperature dependence of two energy scales in cuprates, emphasizing the role of electron-phonon coupling in high-temperature superconductivity.

Findings

High energy kink increases with doping and is temperature independent.

Low energy kink shows non-monotonic doping dependence and sharp enhancement below Tc.

Results support electron-phonon interactions as key to understanding cuprate superconductivity.

Abstract

High resolution laser-based angle-resolved photoemission measurements have been carried out on Bi2Sr2CuO6+d superconductor covering a wide doping range from heavily underdoped to heavily overdoped samples. Two obvious energy scales are identified in the nodal dispersions: one is the well-known 50-80 meV high energy kink and the other is <10 meV low energy kink. The high energy kink increases monotonously in its energy scale with increasing doping and shows weak temperature dependence, while the low energy kink exhibits a non-monotonic doping dependence with its coupling strength enhanced sharply below Tc. These systematic investigations on the doping and temperature dependence of these two energy scales favor electron-phonon interactions as their origin. They point to the importance in involving the electron-phonon coupling in understanding the physical properties and the superconductivity mechanism of high temperature cuprate superconductors.