Partially disordered phases in the three-dimensional axial next-nearest-neighbor Ising model with alternating intralayer interactions

We consider the three-dimensional axial next-nearest-neighbor Ising model, which is composed of two kinds of alternately stacked ferromagnetic layers with different intralayer interactions. The finite temperature magnetic phase diagram of this model is investigated by means of the site-dependent molecular-field approximation. The phase diagram shows that there exist the partially disordered phases and the saturated point where critical wave number saturates to 1/4. In addition, it is confirmed that Monte Carlo results are consistent with those of the site-dependent molecular-field approximation.