IFLYSIB   05383
INSTITUTO DE FISICA DE LIQUIDOS Y SISTEMAS BIOLOGICOS
Unidad Ejecutora - UE
artículos
Título:
First- and second-order wetting transitions in confined Ising films in the presence of nonmagnetic impurities: A Monte Carlo simulation study
Autor/es:
S.M. COTES; E. V. ALBANO
Revista:
PHYSICAL REVIEW E - STATISTICAL PHYSICS, PLASMAS, FLUIDS AND RELATED INTERDISCIPLINARY TOPICS
Editorial:
American Physical Society (APS)
Referencias:
Año: 2011
ISSN:
1063-651X
Resumen:
In this work we present the results of a systematic exploration of the effect caused by the introduction of nonmagnetic impurities (or defects) on the stabilization of the interface between two magnetic domains of opposite magnetic orientation. Those defects are simulated as spin vacancies along the center of confined 2D Ising films, which have competing magnetic fields acting on the confinement walls. The calculations are performed for different LxM film sizes, and by using the standard Metropolis dynamics. In the absence of defects, the film is characterized by an interface running along the M-direction, which is induced by the competing surface fields. That interface  undergoes  a localization-delocalization transition that is the precursor of a true wetting transition taking place in the  thermodynamic limit.When the density of defects is relatively low, our results show that the wetting phase transition is of second order, as in the absence of defects. On the other hand, when the density of nonmagnetic impurities is  relatively high, a pinning effect of the interface gives rise to a first-order wetting phase transition.The observed transitions are characterized by measuring relevant properties such as magnetization profiles, cumulants, magnetization fluctuations, etc., as a function of the density of defects. So, our main finding is that the presence of nonmagnetic impurities introduces a rich physical scenary such as a line of second-order wetting transitions (observed for low density of defects) merges into a first-order one just in a tricritical point. Precisely, these two latter findings are the major contribution of our study.  <!-- @page { size: 21.59cm 27.94cm; margin: 2cm } P { margin-bottom: 0.21cm } -->