Regensburg 2007 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
DY: Fachverband Dynamik und Statistische Physik
DY 15: Internal Symposium: Finite size effects at phase transitions
DY 15.1: Hauptvortrag
Dienstag, 27. März 2007, 14:00–14:30, H2
Unconventional types of phase transitions due to interplay of finite size and interfacial effects — •Kurt Binder1, Andrey Milchev1,2, 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.