Ultrafast dynamics of electron-phonon coupling in a metal

TL;DR

This paper uses time-resolved photoemission spectroscopy to investigate ultrafast electron-phonon interactions in a metal, revealing complex dynamics that challenge existing theoretical models.

Contribution

It provides new experimental insights into electron-phonon coupling dynamics in metals under photo-excitation, highlighting discrepancies with current theories.

Findings

Phonon energy does not dominate quasiparticle dynamics.

Electron-phonon coupling effects are observed in real and imaginary self-energy components.

Results differ from behaviors in superconducting materials.

Abstract

In the past decade, the advent of time-resolved spectroscopic tools has provided a new ground to explore fundamental interactions in solids and to disentangle degrees of freedom whose coupling leads to broad structures in the frequency domain. Time- and angle-resolved photoemission spectroscopy (tr-ARPES) has been utilized to directly study the relaxation dynamics of a metal in the presence of electron-phonon coupling. The effect of photo-excitations on the real and imaginary part of the self-energy as well as the time scale associated with different recombination processes are discussed. In contrast to a theoretical model, the phonon energy does not set a clear scale governing quasiparticle dynamics, which is also different from the results observed in a superconducting material. These results point to the need for a more complete theoretical framework to understand electron-phonon interaction in a photo-excited state.