Effective field theory for the Ising film model under a layered magnetic field

Using the effective field theory, we investigate the phase diagrams of the multilayer Ising model under a layered magnetic field With varying the numb er of layers "n": several phases are observed. Moreover, we distinguish two different features with varying magnetic field, corresponding to odd or ev en number "n": The phase diagram of the system with infinite "n" presents t he ferromagnetic and the layered phases which are separated by a first orde r transition line, at low temperatures. However, at high temperatures, this line is found to be of second order with a tricritical end-point.