Phase Transitions and the Magnetic Properties of the Potts Model with Four Spin States on a Hexagonal Lattice in Low Magnetic Fields

摘要

Phase transitions and the magnetic properties of the two-dimensional Potts model with the four spin states on a hexagonal lattice in low magnetic fields are studied using the replica exchange algorithm of the Monte Carlo method. The studies are performed in the magnetic field range of 0.0 <= H <= 3.5 with a step of 0.5. For this H range, the magnetic structures of the ground state are determined. It is found that the first-order phase transition occurs in the whole magnetic field range under study, except for H = 1.5, at which the secondorder phase transition takes place. In the framework of such model, it is demonstrated that the applied magnetic field can lead to a change in the order of the phase transition.