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.

Nonlinear absorption of ultrashort laser pulses in thin metal films

“…3 in Ref. 5). Note that δf is not symmetric around v x = 0, because the initial excitation was not symmetric either.…”

Collective Electron Dynamics in Metallic and Semiconductor Nanostructures

“…1). The Vlasov-Poisson system has been used to study the dynamics of electrons in metal clusters and thin metal films [45,18]. It is appropriate for large excitation energies, for which the electrons' de Broglie wavelength is relatively small, thus reducing the importance of quantum effects in the electron dynamics.…”

“…After saturation, a slowly oscillating regime appears, with period equal to 50ω −1 p ≈ 5.3fs, where ω p = (e 2 n/mε 0 ) 1/2 is the plasmon frequency. This period is close to the time of flight of electrons traveling at the Fermi velocity and bouncing back and forth on the film surfaces (further details are provided in our previous work [18]). …”

“…Our own contribution to this research area has mainly focussed on the nonlinear electron dynamics in thin metal films, where the emergence of ballistic low-frequency oscillations has been pointed out [18].…”

Laser absorption and third-harmonic generation in free-electron nanofilms

“…For cold metal nanofilms, such an approach was used recently. [31][32][33] However, much information about these processes may be obtained already with the somewhat simpler hydrodynamic equations.…”