INVESTIGADORES
DE VIRGILIIS Andres
artículos
Título:
Study of the confined Ising magnet with long-range competing boundary fields
Autor/es:
A. DE VIRGILIIS; E. V. ALBANO; M. MUELLER; K. BINDER
Revista:
JOURNAL OF PHYSICS CONDENSED MATTER
Referencias:
Año: 2005 vol. 17 p. 4579 - 4604
ISSN:
0953-8984
Resumen:
We present extensive Monte Carlo simulations of the Ising film confined in an
L × M
geometry () in the presence of long-range competing magnetic fields
h(n) = h1/n3(n = 1,2,...,L)
which are applied at opposite walls along the
M-direction. Due to the fields, an interface between domains of different orientations that
runs parallel to the walls forms and can be located close to one of the two surfaces or
fluctuate in the centre of the film (localizationdelocalization transition). This transition is
the precursor of the wetting phase transition that occurs in the limit of infinite film
thickness () at the critical curve Tw(h1). For T<Tw(h1)
(T≥Tw(h1)) such an interface is bound to (unbound from) the walls.
We study this transition by measuring the magnetization profiles across the
sample and the distribution function of both the magnetization of the whole
sample and that of the centre of the film as a function of temperature,
T, or strength of
the wall field, h1. We obtain estimates of the size-dependent wetting 'critical' points that allow us to
extrapolate to the thermodynamic limit. Using the results of these extrapolations,
confirmed by independent measurements of the cumulant, we draw the phase diagram of
the wetting transition with long-range surface fields.
We show that, starting from a localized interface well inside the non-wet phase, the
position of the interface diverges exponentially when approaching the transition point, in
contrast to the power-law divergence observed in the case of short-range fields.
The properties of the delocalized interface are also studied. Within the wet phase the width
of the capillary waves broadens the observed interface profiles. The spectrum of capillary
waves is cut off at large wavelengths by the correlation length, , which scales like , similar to the short-range case. Additionally, the interface stiffness is obtained from the
Fourier spectrum of the capillary waves.