By using the variational principle for the Gibbs free energy, based on the Bogoliubov inequality, the magnetic properties of disordered
systems with competing interactions are studied. In our model, we implement periodic boundary conditions stressing on how the number
of first nearest neighbors can modify the magnetism. Concerning the competing interactions, we have considered those values
corresponding to the ternary system FeMnAl. This system exhibits magnetic phases, like the spin-glass behavior, arising from atomic
disorder, bond competition and the dilutor effect of aluminum atoms. In this work we compute the magnetization per site and the
magnetic susceptibility, as a function of temperature, for different values of the coordination number. Results reveal an increase of the
Curie temperature with the number of first nearest neighbors, as well as the existence of a minimum critical coordination number below
which the system becomes paramagnetic. |
