Phys.org  March 13, 2024
Understanding phonon scattering has remained challenging and requires detailed information on interactions between phonons and electrons. An international team of researchers (USA – SLAC National Accelerator Laboratory, Lawrence Livermore National Laboratory, Los Alamos National Laboratory, Sweden, Italy) used an ultrafast electron diffuse scattering technique to resolve the nonequilibrium phonon dynamics in femtosecond–laser-excited tungsten in both time and momentum. They determined transient populations of phonon modes which show strong momentum dependence initiated by electron-phonon coupling. For phonons near Brillouin zone border, they observed a transient rise in their population on a timescale driven by the strong electron-phonon coupling, followed by a slow decay governed by the weaker phonon-phonon relaxation process. They found  that the exceptional harmonicity of tungsten was needed for isolating the two processes, resulting in long-lived nonequilibrium phonons in a pure metal.  According to the researchers their finding highlights that electron-phonon scattering can be the determinant factor in the phonon thermal transport of metals… read more. Open Access TECHNICAL ARTICLE
UEDS experiment of phonon dynamics in W. Credit: SCIENCE ADVANCES, 13 Mar 2024, Vol 10, Issue 11