Finite-size scaling at first- and second-order phase transitions of Baxter-Wu model

Using a finite-size phenomenological theory we investigate the behavior of the Baxter-Wu model for both first- and second-order transitions. In order to distinguish between the two kinds of transition we study the finite-size scaling behavior of the order parameter and the susceptibility of the model. At the critical temperature the known critical exponents of the system govern the scaling behavior, while below the critical temperature the scaling exponents are the dimensionality of the system. The presented scaling theory for the Baxter-Wu model is an appropriate generalization of the corresponding theory of Binder and Landau for the Ising model [Binder and Landau, Phys. Rev. B 30 (1984) 1477]. We perform numerical simulations using standard Monte Carlo techniques and we find that our results are in good agreement with theoretical predictions.