Speaker
Description
Experiments in the time domain allow to determine the electron-boson coupling by determining the second moment of the Eliashberg function $\alpha^2F(\omega)$ from the relaxation time constant of thermalized, hot electrons after optical excitation due to energy dissipation into further degrees of freedom. While this approach works well for conventional superconducting materials, it is under discussion for unconventional superconductors. In this talk time- and angle-resolved photoemission on cuprate and Fe-based superconductors will be presented and the question of thermalized / non-thermalized distributions will be discussed. We show that coupling to specific bosonic excitations inhibits thermalization of the excited electron distribution. Analysis of the actual non-equilibrium distribution provides opportunites to analyze the electron-boson coupling without the assumption of a thermalized electron distribution.
