Antinodal kink in the band dispersion of electron-doped cuprate ${\rm La}_{2-x}{\rm Ce}_x{\rm CuO}_{4\pm\delta}$

TL;DR

This study uses ARPES to systematically investigate the antinodal kink in electron-doped cuprate La2-xCexCuO4, revealing a doping-independent phonon-related feature that is weakly linked to superconductivity.

Contribution

First systematic ARPES analysis of the antinodal kink in electron-doped cuprates across a wide doping range, highlighting phonon involvement and weak coupling to superconductivity.

Findings

Antinodal kink observed around 45 meV for doping levels 0.05-0.19.

Kink position is roughly doping-independent.

Kink persists above 200 K, indicating phonon origin.

Abstract

Angle-resolved photoemission spectroscopy (ARPES) measurements have established the phenomenon of kink in band dispersion of high-$T_{\rm c}$ cuprate superconductors. However, systematic studies of the kink in electron-doped cuprates are still lacking experimentally. We performed $in$-$situ$ ARPES measurements on ${\rm La}_{2-x}{\rm Ce}_x{\rm CuO}_{4\pm\delta}$ (LCCO) thin films over a wide electron doping ($n$) range from 0.05 to 0.23. While the nodal kink is nearly invisible, an antinodal kink around 45 meV, surviving above 200 K, is observed for $n\sim0.05-0.19$, whose position is roughly independent of doping. The fact that the antinodal kink observed at high temperatures and in the highly overdoped region favors the phonon mechanism with contributions from the Cu-O bond-stretching mode and the out-of-plane oxygen buckling mode. Our results also suggest that the antinodal kink of LCCO is only weakly coupled to its superconductivity.