Dynamical behavior of three-dimensional confined Ising systems with short- and long-range competing surface fields.
The dynamical behavior of ferromagnetic Ising films confined in a DxLxL geometry (D<<L,1< or =i< or =D) is studied by means of Monte Carlo simulations when either short- or long-range competing magnetic fields H(i) of equal strength but opposite sign are applied at opposite walls, given by the LxL surfaces. It is well known that, for appropriate choices of the control parameters, these systems exhibit wetting phase transitions that occur in the limit of infinite film thickness at the critical curve Tw(hw) , where hw=H(i=1) is the magnitude of the surface field at the wall. Results of the dynamical approach to equilibrium, at criticality and for the complete wetting regime, obtained by starting the systems from different (far-from equilibrium) initial conditions, are presented and discussed. We determine quite accurately a wetting critical point [Tw=0.8982(57),hw=0.555] for the case of short-range fields, by measuring the detachment of the wetting layer from a wall, which for this type of field obeys a logarithmic dependence on time. For retarded van der Waals forces we obtained [Tw=0.8982,hw=0.449(1)] for the critical point. The scaling behavior of the average position of the interface is also studied for the complete wetting regime at T=0.8982 and in the presence of a bulk magnetic field H=1 . The numerical results are in full agreement with the theoretical expectations for the cases of short-range and long-range (both retarded and nonretarded van der Waals forces) fields, where logarithmic and power-law divergences are found, respectively.
IFLP, Departamento de Física, UNLP, La Plata, Argentina.
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Manias
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De Virgiliis
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Albano
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Müller
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Binder