Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)

O 36.66: Poster

Tuesday, March 15, 2011, 18:30–22:00, P4

Temperature-Dependent Ordering in Au-induced Chains on Ge(001) — Christian Blumenstein¹, •Sebastian Mietke², Jörg Schäfer¹, Sebastian Meyer¹, Michael Lochner², René Matzdorf², and Ralph Claessen¹ — ¹Physikalisches Institut, Universität Würzburg — ²Institut für Physik, Universität Kassel

Atomic nanowires may be formed by self-organization on a semiconductor surface. Their structure and the resulting quasi-one-dimensional character is determined by the choice of metal adatom and the substrate material. It is commonly believed that many of these systems will undergo a Peierls instability upon cooling. Here we scrutinize nanowires realized by Au chains on Ge(001) to investigate the potential occurrence of lattice instabilities. In combining scanning tunneling microscopy with electron diffraction, we find a phase transition, notably occurring at elevated temperature. It is of second order, and leads to a complex ordering with transversal elongations in addition to the c(8×2) reconstruction. However, since it lacks the electronic prerequisites, such as a nesting condition or an energy gap, this excludes a Peierls scenario. Instead, this transition points at cooperative interactions of charge and lattice including the substrate. As important consequence, these chains remain metallic even at low temperature.