Phase Transition in the 3-State Potts Antiferromagnet on the Diced Lattice

We prove that the 3-state Potts antiferromagnet on the diced lattice (dual of the kagome lattice) has entropically driven long-range order at low temperatures (including zero). We then present Monte Carlo simulations, using a cluster algorithm, of the 3-state and 4-state models. The 3-state model has a phase transition to the high-temperature disordered phase at v=eJ-1=-0.860 599±0.000 004 that appears to be in the universality class of the 3-state Potts ferromagnet. The 4-state model is disordered throughout the physical region, including at zero temperature.This work was supported in part by NSF Grant No. PHY-0424082, Spanish MEC Grants No. MTM2005-08618 and No. FIS2004-03767, and Czech Grants No. GACR 201/06/1323 and No. MSM 002162084