Ferroelectrics, 372:47–53, 2008 Copyright © Taylor & Francis Group, LLC ISSN: 0015-0193 print / 1563-5112 online DOI: 10.1080/00150190802381746 Phase Transition and Magnetic Properties of a Decorated Ising Film M. BOUGHRARA, ∗ E. TAIFI, AND M. KEROUAD LPMMS, Department of Physics, University Moulay Isma¨ ıl, Faculty of Sciences, BP 11201, Zitoune, Meknes, Morocco The magnetic properties and the phase diagrams of a decorated Ising film on the cubic lattice are investigated within the framework of an effective field theory based on the use of a probability distribution technique. The system studied consists of two magnetic atoms species A and B with σ A = 1/2 and S B = 1, where the B sites decorate the bonds between A sites. The effect of the crystal field and the thickness of the film, on the behaviour of the system, are examined. We find a number of characteristic phenomena such as the possibility of two compensation points and the double reentrant phenomenon. Keywords Phase diagram; decorated film; compensation point; magnetic properties 1. Introduction Ferrimagnets are materials where ions on different sublattices have opposing magnetic moments which do not exactly cancel even at zero temperature [1]. An intriguing possibility then is the existence, under certain conditions, of a compensation temperature at which the resultant magnetization vanishes [2, 3]. This has obvious technological significance. The study of a decorated Ising spin models has a long history, it is introduced in the literature by Syozi [4] as exactly solvable models in statistical physics. Kaneyoshi [5] has introduced a mixed spin Ising model on the square lattice with spins σ A = 1/2 on the vertices, coupled antiferromagneticly to spins S B > 1/2 decorating the bonds. Some interest phenomena are obtained, in particular, for S B = 1 and negative crystal field anisotropy, the system can present the reentrant phenomenon and one or two compensation points. A. Moutie [6] has studied the effect of a random transverse field on the magnetic properties of a thin film with decorated ferrimagnetic surfaces. A number of interest phenomena are found, such as the possibility of the existence of the compensation points on the surface and in the film. Recently, the study of a decorated Ising model has extended to the simple cubic lattice. Within the framework of an effective field theory with correlation, J. Oitmaa [7] has studied the effect of the anisotropy on the magnetic properties and the phase diagrams of a decorated 3D Ising model. A number of interesting results were obtained; in particular, the system can present the reentrant behaviour, with the possibility of three, two and one phase transitions and zero, one or two compensation points. Received in final form May 24, 2008. ∗ Corresponding author. E-mail: Mordjaoui mourad@yahoo.fr [195]/47