Identification of Nodal Kink in Electron-Doped (Nd_1.85Ce_0.15)CuO₄ Superconductor from Laser-Based Angle-Resolved Photoemission Spectroscopy

¹ National Laboratory for Superconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
² Laboratory for Optics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
³ Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China
⁴ Department of Physics, University of Science and Technology of China, Anhui, China
⁵ Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama Kanagawa, Japan

^a Corresponding author: XJZhou@aphy.iphy.ac.cn

Abstract

High-resolution laser-based angle-resolved photoemission measurements have been carried out on the electron-doped (Nd_1.85Ce_0.15)CuO₄ high temperature superconductor. We have revealed a clear kink at ~60 meV in the dispersion along the (0,0)–(π,π) 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.