Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 119: Non-Equilibrium Daynamics in Light-Driven Materials: Theory Meets Experiment

O 119.1: Vortrag

Freitag, 16. März 2018, 11:30–11:45, MA 141

Long-lasting nonequilibrium in the electron system of laser-excited copper — •Sebastian T. Weber and Baerbel Rethfeld — Department of Physics and Research Center Optimas, University of Kaiserslautern, Erwin Schroedinger-Strasse 46, 67663 Kaiserslautern, Germany

After excitation with an ultra-short laser pulse, the electrons in a metal are in a strong nonequilibrium state. During thermalization, they interact also with the lattice, transferring energy to the phonons. On the basis of complete Boltzmann-type collision integrals, a method allowing to treat materials with an arbitrary density of states has been developed [Phys. Rev. B 87, 035139 (2013)]. This method provides insights into the response of different material classes to ultra-fast laser excitation. Here, we focus on the study of copper which possesses a characteristic densities of states with an elevated area at a certain distance below the Fermi edge.

The results show the thermalization of the electrons towards Fermi distributions in a few femtoseconds. However, electron-phonon coupling hinders the electrons' complete thermalization as long as the quasi-temperatures of subsystems differ from each other. We present results showing these thermal and non-thermal non-equilibria and their timescales of relaxation.