Superconductivity-Induced Self-Energy Evolution of the Nodal Electron of   Optimally-Doped Bi2212
  The temperature dependent evolution of the renormalization effect in optimally-doped Bi2212 along the nodal direction has been studied via angle-resolved photoemission spectroscopy. Fine structure is observed in the real part of the self-energy (Re$\Sigma$), including a subkink and maximum, suggesting that electrons couple to a spectrum of bosonic modes, instead of just one mode. Upon cooling through the superconducting phase transition, the fine structures of the extracted Re$\Sigma$ exhibit a two-processes evolution demonstrating an interplay between kink renormalization and superconductivity. We show that this two-process evolution can be qualitatively explained by a simple Holstein model in which a spectrum of bosonic modes is considered. 
W. S. Lee, W. Meevasana, S. Johnston, D. H. Lu, I. M. Vishik, R. G.   Moore, H. Eisaki, N. Kaneko, T. P. Devereaux, and Z. X...