Regensburg 2007 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 15: Phase transitions I

MM 15.4: Vortrag

Dienstag, 27. März 2007, 11:00–11:15, H4

Laser-induced phase transition in As under pressure — •Nils Huntemann, Eeuwe Sieds Zijlstra, and Martin Garcia — Theoretische Physik, Fachbereich Naturwissenschaften, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany

It has been experimentally shown [U. Häussermann et al., J. Am. Chem. Soc. 124, 15359 (2002)] that As undergoes a structural transition from the A7 to the simple cubic (SC) structure for increasing pressure. This phase transition occurs in thermodynamical equilibrium. In the last years different nonthermal, ultrafast structural changes have been induced in solids by means of femtosecond laser pulses [A. Cavalleri et al., Phys. Rev. Lett. 87, 237401 (2001)]. Based on first-principles electronic structure calculations we explored the possibility of inducing nonthermal structural changes in As by ultrashort laser pulses. For this purpose, we determined the potential energy surface (electronic free energy) as a function of the lattice parameters and atomic coordinates for different electronic temperatures, which simulates the ultrafast laser heating of the electrons. Our results indicated that a laser-induced phase transition may occur in As under a pressure of ∼ 20 GPa.