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

TL;DR

This study uses laser-based ARPES to measure the electron self-energy and gap function in Bi_2Sr_2CaCu_2O_8, revealing detailed features that inform the understanding of high-temperature superconductivity.

Contribution

First experimental extraction of complex electron self-energy and gap function in Bi_2Sr_2CaCu_2O_8 using high-resolution laser ARPES.

Findings

Identification of features at ~54 meV and ~40 meV in self-energy and gap function.

Observation of Bogoliubov-like quasiparticle dispersion at low temperature.

Detection of multiple structures in the electron self-energy and gap function.

Abstract

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.