Electron Cooling and Debye-Waller Effect in Photoexcited Bismuth

Brice Arnaud (1) , Y. Giret (2)

1 IPR - Institut de Physique de Rennes
2 Institute of Scientific and Industrial Research

By means of first principles calculations, we compute the effective electron-phonon coupling constant G0 governing the electron cooling in photoexcited bismuth. G0 strongly increases as a function of electron temperature, which can be traced back to the semimetallic nature of bismuth. We also use a thermodynamical model to compute the time evolution of both electron and lattice temperatures following laser excitation. Thereby, we simulate the time evolution of (1 -1 0), (-2 1 1) and (2 -2 0) Bragg peak intensities measured by Sciaini et al. [Nature (London) 458, 56 (2009)NATUAS0028-0836] in femtosecond electron diffraction experiments. The effect of the electron temperature on the Debye-Waller factors through the softening of all optical modes across the whole Brillouin zone turns out to be crucial to reproduce the time evolution of these Bragg peak intensities.

Mots clés: Density functional theory; local density approximation; gradient and other corrections; Phonon-electron interactions; Statistical mechanics of lattice vibrations and displacive phase transitions; Ultrafast pump/probe spectroscopy

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Brice Arnaud, Y. Giret. Electron Cooling and Debye-Waller Effect in Photoexcited Bismuth. Physical Review Letters, 2013, 110 (1), pp.16405. ⟨10.1103/PHYSREVLETT.110.016405⟩. ⟨hal-00805890⟩