Extraction of Electron Self-Energy and Gap Function in the   Superconducting State of Bi_2Sr_2CaCu_2O_8 Superconductor via Laser-Based   Angle-Resolved Photoemission
  Super-high resolution laser-based angle-resolved photoemission measurements have been performed on a high temperature superconductor Bi_2Sr_2CaCu_2O_8. The band back-bending characteristic of the Bogoliubov-like quasiparticle dispersion is clearly revealed at low temperature in the superconducting state. This makes it possible for the first time to experimentally extract the complex electron self-energy and the complex gap function in the superconducting state. The resultant electron self-energy and gap function exhibit features at ~54 meV and ~40 meV, in addition to the superconducting gap-induced structure at lower binding energy and a broad featureless structure at higher binding energy. These information will provide key insight and constraints on the origin of electron pairing in high temperature superconductors. 
Wentao Zhang, Jin Mo Bok, Jae Hyun Yun, Junfeng He, Guodong Liu, Lin   Zhao, Haiyun Liu, Jianqiao Meng, Xiaowen Jia, Yingyin...
cond-mat.supr-con cond-mat.str-el