On the order of the phase transition in the 3D three-state Potts model with anti-ferromagnetic next-to-nearest neighbour coupling

We investigate the order of the phase transition in the three dimensional, three-state Potts model with anti-ferromagnetic next-to-nearest neighbour (NNN) coupling in a high statistics, finite size scaling study. On L3 lattices with L ranging from 20 to 48 with the relative strength of the NNN coupling, γ, fixed to -0.2, we find a first order phase transition. The onset of the finite size scaling behaviour seems to occur later compared to the γ=0.0 case. The discontinuity in the order parameter is of the same magnitude in both cases, while the latent heat decreases by a factor of two