THE ANTIFERROMAGNETIC 3-STATE POTTS-MODEL ON A TRIANGULAR LATTICE

We study the phase diagram of the three-state Potts model on a triangular lattice with antiferromagnetic interactions between nearest-neighbor spins. The cell-spin analysis for the isotropic model reveals that the symmetry of the ground states is dual to the symmetry of the n=3 cubic model which is known to exhibit a first-order phase transition. For the anisotropic model, the chirality appears between the ground states. Monte Carlo simulations show that a first-order line merges from the KDP point and separates completely an antiferromagnetic ordered phase and a disordered phase.