Ultrafast dynamics of electron-phonon coupling in a metal

¹ Department of Physics, Pusan National University - Busan 46241, South Korea
² Materials Sciences Division, Lawrence Berkeley National Laboratory - Berkeley, CA 94720, USA
³ School of Physics and Astronomy, Shanghai Jiao Tong University - Shanghai 200240, China
⁴ Department of Applied Physics, Tohoku University - Sendai 980-8579, Japan
⁵ Department of Engineering and Applied Sciences, Sophia University - Tokyo 102-8554, Japan
⁶ Department of Physics, University of California - Berkeley, CA 94720, USA

Received: 13 April 2019
Accepted: 17 June 2019

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 with 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.