Interlayer-interaction dependence of latent heat in the Heisenberg model on a stacked triangular lattice with competing interactions

We study the phase transition behavior of a frustrated Heisenberg model on a stacked triangular lattice by Monte Carlo simulations. The model has three types of interactions: the ferromagnetic nearest-neighbor interaction J ₁ and antiferromagnetic third nearest-neighbor interaction J ₃ in each triangular layer and the ferromagnetic interlayer interaction J_⊥. Frustration comes from the intralayer interactions J₁ and J₃. We focus on the case that the order parameter space is SO(3)×C₃. We find that the model exhibits a first-order phase transition with breaking of the SO(3) and C₃ symmetries at finite temperature. We also discover that the transition temperature increases but the latent heat decreases as J _⊥/J₁ increases, which is opposite to the behavior observed in typical unfrustrated three-dimensional systems.