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HL: Fachverband Halbleiterphysik
HL 26: Ultra-fast phenomena
HL 26.9: Vortrag
Mittwoch, 14. März 2018, 11:45–12:00, EW 202
Decay channels of the coherently excited A1g phonon in antimony — •Sergej Krylow1, Eeuwe S. Zijlstra1, Fairoja Cheenicode Kabeer2, Tobias Zier1, Bernd Bauerhenne1, and Martin E. Garcia1 — 1Universität Kassel, Theoretische Physik II — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin
The analysis of phonon decay channels is of great importance in order to understand the dynamics of a system excited by an ultrafast laser pulse. Femtosecond laser excitation of Antimony generates a coherent A1g phonon and, at the same time, softens the covalent bonds between the atoms. Both effects crucially affect the dynamics of antimony after laser excitation. It is in general difficult to disentangle the influence of both effects and to extract information about the decay channels of the coherent A1g phonon. In this work we develop a method to analyze the phonon decay channels in ultrafast excited antimony using ab initio molecular dynamic simulations. Our simulations allow us to account for all phonon degrees of freedom, which was previously not possible. In particular we find, that at low excitation densities the dominating decay channel is a third order scattering process for which one A1g phonon decays into two other phonons. At high excitation densities a fourth order scattering process becomes dominant for that two A1g phonons decay into two phonons.