Regensburg 2007 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 30: Poster II
DY 30.30: Poster
Donnerstag, 29. März 2007, 16:00–18:00, Poster D
Reduction of surface coverage of finite systems due to geometrical steps — •Klaus Morawetz1,2, Carsten Olbrich3, Sibylle Gemming4, and Michael Schreiber1 — 1Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany — 2Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany — 3School of Engineering and Science, Jacobs University Bremen, 28725 Bremen, Germany — 4Forschungszentrum Rossendorf, PF 51 01 19, 01314 Dresden, Germany
The coverage of vicinal, stepped surfaces with molecules is simulated with the help of a two-dimensional Ising model including local distortions and an Ehrlich-Schwoebel barrier term at the steps. An effective two-spin model is capable to describe the main properties of this distorted Ising model. It is employed to analyze the behavior of the system close to the critical points. Within a well-defined regime of bonding strengths and Ehrlich-Schwoebel barriers we find a reduction of coverage (magnetization) at low temperatures due to the presence of the surface step. This results in a second, low-temperature transition besides the standard Ising order-disorder transition. The additional transition is characterized by a divergence of the susceptibility as a finite-size effect. Due to the surface step the mean-field specific heat diverges with a power law. [cond-mat/0608013]