Universality aspects of the two-dimensional spin-1 Baxter-Wu model in a crystal field

L. N. Jorge, P. H. L. Martins, Cláudio José DaSilva +2 more

L. N. Jorge, L. S. Ferreira, Álvaro A. Caparica

L. N. Jorge, L. S. Ferreira, Salviano A. Leão +1 more

Nikolaos G. Fytas, Alexandros Vasilopoulos, Erol Vatansever +2 more

Abstract We investigate aspects of universality in the two-dimensional (2D) spin-1 Baxter-Wu model in a crystal field Δ using a parallel version of the multicanonical algorithm employed at constant temperature T. A detailed finite-size scaling analysis in the continuous regime of the Δ – T phase diagram of the model indicates that the transition belongs to the universality class of the 4-state Potts model. The presence of first-order-like finite-size effects that become more pronounced as one approaches the pentacritical point of the model is highlighted and discussed.

Henk W. J. Blöte, M. P. Nightingale

Daniele Alves Dias, J. C. Xavier, J. A. Plascak

The phase diagram and the critical behavior of the spin-1 and the spin-3/2 two-dimensional Baxter-Wu model in a crystal field are studied by conventional finite-size scaling and conformal invariance theory. The phase diagram of this model, for the spin-1 case, is qualitatively the same as those of the diluted 4-states Potts model and the spin-1 Blume-Capel model. However, for the present case, instead of a tricritical point one has a pentacritical point for a finite value of the crystal field, in disagreement with previous work based on finite-size calculations. On the other hand, for the spin-3/2 case, the phase diagram is much richer and can present, besides a pentacritical point, an additional multicritical end point. Our results also support that the universality class of the critical behavior of the spin-1 and spin-3/2 Baxter-Wu model in a crystal field is the same as the pure Baxter-Wu model, even at the multicritical points.