Identification of Nodal Kink in Electron-Doped (Nd$_{1.85}$Ce$_{0.15}$)CuO$_4$ Superconductor from Laser-Based Angle-Resolved Photoemission Spectroscopy

TL;DR

This study uses laser-based ARPES to identify a 60 meV kink in the electron dispersion of Nd$_{1.85}$Ce$_{0.15}$CuO$_4$, indicating electron-boson coupling, likely phonons, suggesting a universal feature in cuprate superconductors.

Contribution

First observation of a nodal kink in electron-doped cuprate superconductor using laser ARPES, highlighting universal electron-boson coupling in high-Tc cuprates.

Findings

Detected a 60 meV kink in dispersion

Observed peak-dip-hump spectral feature

Indicated phonons as the likely boson

Abstract

High-resolution laser-based angle-resolved photoemission measurements have been carried out on the electron-doped (Nd$_{1.85}$Ce$_{0.15}$)CuO$_4$ high temperature superconductor. We have revealed a clear kink at $\sim$60 meV in the dispersion along the (0,0)-($\pi$,$\pi$) nodal direction, accompanied by a peak-dip-hump feature in the photoemission spectra. This indicates that the nodal electrons are coupled to collective excitations (bosons) in electron-doped superconductors, with the phonons as the most likely candidate of the boson. This finding has established a universality of nodal electron coupling in both hole- and electron-doped high temperature cuprate superconductors.