Vlasov simulations of ultrafast electron dynamics and transport in thin metal films

Abstract

The ultrafast dynamics of electrons and ions in thin metal films has been investigated using a semiclassical model based on self-consistent Vlasov simulations. The Vlasov equation is solved using a very accurate Eulerian scheme that preserves the fermionic character of the electron distribution for all times. With this technique, the electronic transport and thermalization are studied on a time scale of over 150 plasmon cycles. Our results demonstrate that heat transport occurs at a velocity close to the Fermi velocity, in agreement with experimental measurements in thin gold films. We also show that (i) internal electron thermalization can be achieved without including any binary electron-electron collisions and (ii) nonequilibrium electrons begin to interact with the lattice well before the internal electron thermalization is completed. These effects are considerably enhanced by the interaction of nonequilibrium electrons with the film surfaces.