Direct observation of the lattice dynamics of transition metals using ultrafast electron diffraction

TL;DR

This study uses ultrafast electron diffraction to directly observe lattice dynamics in transition metals, revealing how electron-phonon interactions influence lattice heating and dynamics with quantitative coupling constants.

Contribution

It provides the first direct observation of lattice dynamics in transition metals using ultrafast electron diffraction and quantitatively evaluates electron-phonon coupling constants.

Findings

Diffraction intensity suppression occurs within a few picoseconds post-photoexcitation.

Electron-phonon coupling constants for Au, Cu, and Mo are quantitatively determined.

Lattice dynamics variations are explained by elemental electronic structure and atomic mass.

Abstract

We report the lattice dynamics of transition metal thin films by using the ultrafast electron diffraction. We observe a suppression of the diffraction intensity in a few picosecond after the photoexcitation, which is directly interpreted as the lattice heating via the electron-phonon interaction. The electron-phonon coupling constants for Au, Cu and Mo are quantitatively evaluated by employing the two-temperature model, which are consistent with those obtained by optical pump-probe methods. The variation in the lattice dynamics of the transition metals are systematically explained by the strength of the electron-phonon coupling, arising from the elemental dependence of the electronic structure and atomic mass.