Ground-State crossover in the quasi-Two-Dimensional classical heisenberg model with dipolar-Type interaction

We have studied the quasi-two-dimensional Heisenberg model with nearest-neighbor dipolar interaction by using a Monte Carlo simulation. By varying the dipolar coupling magnitude D or the anisotropy ratio λ of the interlayer exchange interaction to the intralayer one, crossovers between different ground-states were observed. The phase boundaries in the (D, λ) space were calculated from the ground-state energies, which are in agreement with the Monte Carlo results. Our Monte Carlo results were compared with experimental data on (C_nH_2n+1NH₃)₂MnCl₄.