Nature of phase transitions in $F$ coupled $q$-state Potts models

Yerali Gandica, Silvia Chiacchiera

Published 2015-11-21Version 1

We study $F$ coupled $q$-state Potts models in a two-dimensional square lattice. The interaction between the different layers is attractive, to favour a simultaneous alignment in all of them. The nature of the phase transition for zero field is numerically determined for $F=2,3$. Using the Lee-Kosterlitz method, we find that it is continuous for $q=2$, whereas it is abrupt for $q>2$. When a continuous phase transition takes place, we also analyze the properties of the geometrical clusters. This allows us to determine the fractal dimension $D$ of the incipient infinite cluster and to corroborate the nature of the phase transition via finite-size scaling and data collapse. A mean-field approximation of the model, from which some general trends can be determined, is presented too. Finally, since this lattice model has been recently considered as a thermodynamic counterpart of the Axelrod model of social dynamics, we discuss our results in connection with this one.