Identification of Nodal Kink in Electron-Doped   (Nd$_{1.85}$Ce$_{0.15}$)CuO$_4$ Superconductor from Laser-Based   Angle-Resolved Photoemission Spectroscopy
  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. 
Haiyun Liu, Guodong Liu, Wentao Zhang, Lin Zhao, Jianqiao Meng,   Xiaowen Jia, Xiaoli Dong, Wei Lu, Guiling Wang, Yong Zhou,...