Quasiwetting and morphological phase transitions in confined far-from-equilibrium magnetic thin films

摘要

The growth of confined magnetic films with ferromagnetic interactions between nearest-neighbor spins is studied in a stripped (1+1)-dimensional rectangular geometry. Magnetic films are grown irreversibly by adding spins at the boundaries of the growing interface. A competing situation with two opposite short range surface magnetic fields of the same magnitude is analyzed. Due to the antisymmetric condition considered, an interface between domains with spins having opposite orientations develops along the growing direction. Such interface undergoes a localization-delocalization transition that is identified as a quasiwetting transition, in qualitative agreement with observations performed under equilibrium conditions. In addition, the film also exhibits a growing interface that undergoes morphological transitions in the growth mode. It is shown that as a consequence of the nonequilibrium nature of the investigated model, the subtle interplay between finite-size effects, wetting, and interface growth mechanisms leads to more rich and complex physical features than in the equilibrium counterpart. Indeed, a phase diagram that exhibits eight distinct regions is evaluated and discussed. In the thermodynamic limit, the whole ordered phase (which contains the quasiwetting transition) collapses, while within the disordered phase, standard extrapolation procedures show that only two regions are present in the phase diagram of the infinite system. (C) 2002 American Institute of Physics. [References: 37]