Eur. Phys. J. B 62, 311-317 (2008)
https://doi.org/10.1140/epjb/e2008-00168-y

Reduction of surface coverage of finite systems due to geometrical steps

¹ Forschungszentrum Dresden-Rossendorf, PF 51 01 19, 01314 Dresden, Germany
² Max-Planck-Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden, Germany
³ Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz, Germany
⁴ Jacobs University Bremen gGmbH, 28759 Bremen, Germany

Corresponding author: ^a morawetz@physik.tu-chemnitz.de

Received: 8 December 2007
Revised: 19 March 2008
Published online: 19 April 2008

Abstract

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.