Interactions between the lattice and charge carriers can drive the formation of phases and ordering phenomena that give rise to conventional superconductivity, insulator-to-metal transitions, and charge-density waves. These couplings also play a determining role in properties that include electric and thermal conductivity. Ultrafast electron diffuse scattering (UEDS) has recently become a viable laboratory-scale tool to track energy flow into and within the lattice system across the entire Brillouin zone, and deconvolves interactions in the time domain. Here, we present a detailed quantitative framework for the interpretation of UEDS signals, ultimately extracting the phonon mode occupancies across the entire Brillouin zone. These transient populations are then used to extract momentum- and mode-dependent electron-phonon and phonon-phonon coupling constants. Results of this analysis are presented for graphite, which provides complete information on the phonon-branch occupations and a determination of the A1′ phonon mode-projected electron-phonon coupling strength ⟨ge,A1′2⟩=0.035±0.001 eV2 that is in agreement with other measurement techniques and simulations.
@article{arxiv.1908.02795,
title = {Time- and momentum-resolved phonon population dynamics with ultrafast electron diffuse scattering},
author = {Laurent P. René de Cotret and Jan-Hendrik Pöhls and Mark J. Stern and Martin R. Otto and Mark Sutton and Bradley J. Siwick},
journal= {arXiv preprint arXiv:1908.02795},
year = {2019}
}