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DS: Fachverband Dünne Schichten

DS 45: Poster IV: One-Dimensional Metals: Reality or Fiction

DS 45.20: Poster

Donnerstag, 3. April 2014, 16:00–19:00, P1

Proof of First Order: The (4x2)<>(8x2) Phase Transition in the Indium on Si(111) Atomic Wire system — F. Klasing, T. Frigge, B. Hafke, V. Tinnemann, B. Krenzer, A. Hanisch-Blicharski, and •M. Horn-von Hoegen — Fakultät für Physik, Universität Duisburg-Essen

The In induced (4x1) reconstruction on Si(111) is a prototype for an atomic wire type arrangement of metal atoms on a surface. It has attracted much attention because the In wires undergo a reversible Peierls like phase transition at Tc = 130 K to a (8x2) reconstructed groundstate. In a high resolution LEED study we observed the existence of a robust hysteresis loop upon slow increase and decrease of the sample temperature at Tc. The critical temperatures of the transition are T+c = 135 K and T-c = 125 K for increasing and decreasing temperatures, respectively. The width of the hysteresis loop of 8.6 K is almost independent on the heating and cooling rate and is thus direct evidence for the existence of an energy barrier between the (8x2) ground state and the (4x1) excited state. It unambiguously answers the question about the nature of the phase transition: it is first order.