Phonon-induced long-lasting nonequilibrium in the electron system of a laser-excited solid

Abstract

Electron-electron thermalization and electron-phonon relaxation processes in laser-excited solids are often assumed to occur on different timescales. This is true for the majority of the conduction band electrons in a metal. However, electron-phonon interactions can influence the thermalization process of the excited electrons. We study the interplay of the underlying scattering mechanisms for the case of a noble metal with help of a set of complete Boltzmann collision integrals. We trace the transient electron distribution in copper and its deviations from a Fermi-Dirac distribution due to the excitation with an ultrashort laser pulse. We investigate the different stages of electronic nonequilibrium after an excitation with an ultrashort laser-pulse of 800 nm wavelength and 10 fs pulse duration. Our calculations show a strong nonequilibrium during and directly after the end of the laser pulse. Subsequently, we find a fast thermalization of most electrons. Surprisingly, we observe a long-lasting nonequilibrium, which can be attributed to the electron-phonon scattering. This nonequilibrium establishes at energies around peaks in the density of states of the electrons and persists on the timescale of electron-phonon energy relaxation. It influences in turn the electron phonon coupling strength.

References in corpus (3)

• Theory of Out-of-Equilibrium Ultrafast Relaxation Dynamics in Metals
• Thermalization in simple metals: The role of electron-phonon and phonon-phonon scatterings
• Relaxation of a nonequilibrium phonon distribution induced by femtosecond laser irradiation

Cited by in corpus (9)

• Theory of out-of-equilibrium electron and phonon dynamics in metals after ultrafast laser excitation
• Wavelength-dependent reflectivity changes on gold at elevated electronic temperatures
• Microscopic non-equilibrium energy transfer dynamics in a photoexcited metal/insulator heterostructure
• Ultrafast demagnetization in ferromagnetic materials: Origins and progress
• Implementation of the electronic non-equilibrium in the two-temperature model
• Electronic nonequilibrium effect in ultrafast-laser-irradiated solids
• Energy relaxation and electron-phonon coupling in laser-excited metals
• Non-thermal electrons open the non-equilibrium pathway of the phase transition in FeRh
• Phonon-dominated energy transport in purely metallic heterostructures