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K: Fachverband Kurzzeitphysik
K 5: Laser Applications and Laser Matter Processing II
K 5.4: Vortrag
Mittwoch, 2. März 2016, 12:20–12:40, f428
Influence of a femtosecond-laser pulse on the Peierls distortion in antimony — •Bernd Bauerhenne1,2, Eeuwe S. Zijlstra1,2, and Martin E. Garcia1,2 — 1Theoretical Physics, University of Kassel, Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany — 2Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), Heinrich-Plett-Strasse 40, D-34132 Kassel, Germany
Antimony crystallizes in the rhombohedral A7 structure, which can be constructed from a simple cubic lattice by rombohedrally distorting it along a body diagonal. This distortion can be described in terms of an internal lattice parameter z. Under ambient conditions, antimony prefers z=0.2336 instead of z=0.25, which corresponds to the simple cubic lattice. This so-called Peierls distortion can be easily seen in the atomic structure, which consists of layers with alternating short and long distances that become equal for z=0.25. Excitation by an intense femtosecond-laser pulse increases the equilibrium position of z and, consequently, excites displacively the A1g phonon, which corresponds to a movement of the before-mentioned atomic layers against each other. For a sufficiently high laser excitation the A1g oscillation exceeds z=0.25 and the alternation of short an long interplanar distances is inverted. We studied this Peierls inversion in dependence of the laser excitation by means of large cell ab inito molecular dynamics simulations and obtained the range of excitations that can be used to achieve this process.