Reduction of surface coverage of finite systems due to geometrical steps


Reduction of surface coverage of finite systems due to geometrical steps

Morawetz, K.; Olbrich, C.; Gemming, S.

The coverage of vicinal, stepped surfaces with molecules is simulated with the help of a two-dimensional Ising model including local distortions and a Schwoebel barrie 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 Schwoebel barriers we find a reduction of coverage (magnetization) 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 and the magnetization as finite-size effects. Due to the surface step the specific heat diverges with a power law.

Keywords: Monte-Carlo simulation; Ising model; finite-size effects; mean-field model; 2D square lattice; Schwoebel barrier

Permalink: https://www.hzdr.de/publications/Publ-8695
Publ.-Id: 8695