Dresden 2014 – wissenschaftliches Programm
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SYOM: Symposium One-dimensional Metals: Reality or Fiction
SYOM 2: Posters: One-Dimensional Metals: Reality or Fiction (jointly organized by DS, HL, O, TT)
SYOM 2.19: Poster
Donnerstag, 3. April 2014, 16:00–19:00, P1
An Atomistic Picture of Charge Density Wave Formation at Surfaces: Indium Atomic Wires on Si(111) — S. Wall1, T. Frigge1, B. Hafke1, V. Tinnemann1, B. Krenzer1, S. Wippermann2, S. Sanna2, F. Klasing1, A. Hanisch-Blicharski1, W.G. Schmidt2, and •M. Horn-von Hoegen1 — 1Fakultät für Physik, Universität Duisburg-Essen — 2Fachbereich Physik, Universität Paderborn
Ultrafast time-resolved reflection high energy electron diffraction was employed to investigate the dynamics of the Peierls-instability-driven phase transition on the (8x2) In/Si(111) surface. At 20 K, far below the critical temperature of 90 K, the (8x2)-(4x1) phase transition is electronically driven through weak excitation with a fs-laser pulse and results in a long-lasting super-cooled excited (4x1) phase. The immediate recovery of the low temperature groundstate is hindered by an activation barrier for the collective motion of the atoms. The recovery of the (8x2) ground state on a timescale of 500 ps is then only triggered by adsorbates that act as nucleation seeds. With increasing density of pre-existing adsorbates the recovery to the groundstate proceeds much faster. The surface unit cells fall back into their ground state one at a time, one-dimensionally like a row of falling dominoes. The phase front propagates at about 100 m/s, comparable to the speed of sound.