Identification of Nodal Kink in Electron-Doped (Nd1.85Ce0.15)CuO4 Superconductor from Laser-Based Angle-Resolved Photoemission Spectroscopy

High-resolution laser-based angle-resolved photoemission measurements have been carried out on the electron-doped (Nd1.85Ce0.15)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.