Electron Kinetics Induced by Ultrafast Photoexcitation of Warm Dense Matter in a 30-nm-Thick Foil

Z. Chen, Y. Y. Tsui, M. Z. Mo, R. Fedosejevs, T. Ozaki, V. Recoules, P. A. Sterne, and A. Ng

Phys. Rev. Lett. 127, 097403 – Published 27 August 2021

Abstract

We report on the study of electron kinetics induced by intense femtosecond (fs) laser excitation of electrons in the $5 d$ band of Au. Changes in the electron system are observed from the temporal evolution of ac conductivity and conduction electron density. The results reveal an increase of electron thermalization time with excitation energy density, contrary to the Fermi-liquid behavior of the decrease of thermalization time associated with the heating of conduction electrons. This is attributed to the severe mitigation of photoexcitation by Auger decay. The study also uncovers the shortening of $5 d$ hole lifetime with the increase of photoexcitation rates. These unique findings provide valuable insights for understanding electron kinetics under extreme nonequilibrium conditions.

Received 13 July 2019
Revised 16 March 2021
Accepted 11 June 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.097403

Physics Subject Headings (PhySH)

Electron relaxation Electron-phonon coupling Electronic structure

Elemental metals

Optical absorption spectroscopy Photoexcitation

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Z. Chen ^1,*,‡, Y. Y. Tsui¹, M. Z. Mo ^1,‡, R. Fedosejevs¹, T. Ozaki², V. Recoules³, P. A. Sterne⁴, and A. Ng^5,†

¹Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G-2V4, Canada
²INRS-EMT, University of Quebec, Varennes, Quebec J3X-1S2, Canada
³CEA, DAM, DIF, 91297 Arpajon Cedex, France
⁴Lawerence Livermore National Laboratory, Livermore, California 94550, USA
⁵Department of Physics and Astronomy, University of British Colombia, Vancouver, British Colombia V6T-1Z1, Canada