Lattice model for exchange-coupled ferromagnetic multilayer systems

We present a variational method with the layer magnetization angle as the variational parameter, and Hostein-Primakoff transformation is applied to the variational Hamiltonian. The magnetization of a ferromagnetic superlattice system with interactions between magnetic layers with perpendicular and in-plane easy axes is estimated. Numerical results on the magnetization configurations under different applied fields, critical field, and critical anisotropic parameter are reported.