line: magnetization of interface magnetic layers, green line: magnetization of interior magnetic layers, blue line: polarization of interface ferroelectric layers, purple line: polarization of interface ferroelectric layers ; (c) Susceptibilities versus T , with the same color code. J m = 1, J mf 1 = −0.15, J mf 2 = −0.135 corresponding to the GS with energy E 1 . B. Particular Case J mf 1 = J mf 2In this section we present the results of the MC simulations in the particular case where J mf 1 = J mf 2 . We will compare these results with results from the MF theory.Results for the temperature dependence of layer magnetizations, polarizations, and susceptibilities of the system are shown in Fig. 6 for J m = J f = 1, J mf = J mf 1 = J mf 2 = −0.15, −0.55. For J mf , these curves present a sharp second-order transitions at T m c 1.32 for magnetic layers and T f c 1.84 for ferroelectric layers.The results with an external magnetic field H z = 0.7 are shown in Fig. 7 for the order