Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 30: 1D Metal Wires on Semiconductors I
O 30.10: Vortrag
Dienstag, 8. März 2016, 13:00–13:15, S052
Atomistic Mechanism and Dynamics of the Optically Induced In/Si (111) (8x2)-(4x1) Phase Transition — •Andreas Lücke1, Simone Sanna1, Uwe Gerstmann1, Stefan Wippermann2, and Wolf Gero Schmidt1 — 1Lehrstuhl für Theoretische Physik, Universität Paderborn, 33095 Paderborn, Germany — 2Interface Chemistry and Surface Engineering Department Max-Planck-Institute for Iron Research GmbH, 40237 Düsseldorf, Germany
The In-Si(111)(8x2)/(4x1) nanowire array features a Peierls instability-driven phase transition, the mechanism of which has been controversial since its discovery, cf. Ref. [1-3]. Experimentally it has been shown that the insulating (8x2) phase undergoes a phase transition towards the metallic (4x1) phase upon optical excitation far below the critical temperature [4]. Here we rationalize this finding by means of ab-initio total-energy and electronic-structure calculations and provide atomistic insight into the driving force and the dynamics of the optically driven phase transition by performing molecular dynamics simulations on excited-state potential energy surfaces. In particular we relate the phase transition to the population/depopulation of specific surface bonds that excite soft phonon modes. Our results rationalize recent findings from ultra-fast time-resolved electron diffraction.
1. H. W. Yeom, et al. Phys. Rev. Lett. 82, 4898 (1999).
2. J. R. Ahn, et al. Phys. Rev. Lett. 93, 106401 (2004).
3. S. Wippermann, et al., Phys. Rev. Lett. 105, 126102 (2010).
4. S. Wall et al., Phys. Rev. Lett. 109, 186101 (2012).