Regensburg 2007 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 15: Internal Symposium: Finite size effects at phase transitions

DY 15.1: Invited Talk

Tuesday, March 27, 2007, 14:00–14:30, H2

Unconventional types of phase transitions due to interplay of finite size and interfacial effects — •Kurt Binder¹, Andrey Milchev^1,2, and Marcus Mueller³ — ¹Institut für Physik, Johannes Gutenberg Universität, 55099 Mainz — ²Institute for Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria — ³Institut für Theoretische Physik, Universität Göttingen, 37077 Göttingen

As generic system for confined nano systems, Ising models are considered confined between “competing walls" on which surface fields of opposite sign act. Such systems do not acquire a nonzero total magnetization at the transition temperature of the bulk, since domains of opposite magnetization are stabilized. At a lower temperature, a magnetization appears, discontinuously, in the thermodynamic limit, though this transition can be the limiting case of a second order transitions. Depending on the geometry, this transition is related to wetting corner filling, or cone filling transitions. Phenomenological finite size scaling concepts about these transitions are discussed, and evidence from Monte Carlo simulations is presented. The double-pyramide geometry can be modeled by a Landau-type free energy, but with size-dependent coefficients.