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K: Fachverband Kurzzeitphysik

K 3: Laser Applications and Laser Matter Interactions I

K 3.5: Vortrag

Dienstag, 1. März 2016, 16:10–16:30, f428

Crystal-momentum resolved analysis of femtosecond-laser induced ultrafast melting in silicon — •Tobias Zier, Eeuwe S. Zijlstra, and Martin E. Garcia — Theoretische Physik, Universität Kassel, Germany

The phenomenon of ultrafast melting, the structural disordering within several hundreds of femtoseconds after an irradiation with an ultrashort laser pulse, in silicon is a subject of interest since several decades. Whereas it is by now well understood that it originates from a non-equilibrium state, in which the electronic system has a much higher temperature (several 10 000 K) than the ions, the microscopic trajectories of the atoms are still obscure. We used our ab initio code CHIVES to perform MD-Simulations of supercells with up to 512 atoms and analyzed the data by projecting the atomic motion onto different phonon directions in order to study in which direction the crystal is melting. We surprisingly found that our result depends on the laser fluence.