Phase Diagram of the Square-Lattice Three-State Potts Antiferromagnet with Staggered Polarization Field

摘要

We study a square-lattice three-state Potts antiferromagnet with a staggeredpolarization field at finite temperature. Numerically treating the transfermatrices, we determine two phase boundaries separating the model-parameterspace into three parts. We confirm that one of them belongs to theferromagnetic three-state Potts criticality, which is in accord with a recentprediction, and another to the Ising type; these are both corresponding to themassless renormalization-group flows stemming from the Gaussian fixed points.We also discuss a field theory to describe the latter Ising transition.