Theoretical study of the intrinsic magnetic properties of disordered Fe1-xRux alloys: a mean-field approach

The magnetic properties of the Fe1-xRux alloy system for 0≤x≤0.10 are studied by using a mean-field approximation based on the Bogoliubov inequality. Ferromagnetic Fe-Fe spin correlations and antiferromagnetic Fe-Ru and Ru-Ru exchanges have been considered for describing the temperature dependence of the Curie temperature and low temperature magnetization. A composition dependence has been imposed in the exchange couplings, as indicated by experiments. From a procedure of least-square fitting to the experimental results an estimation of the interaction parameters was obtained, which yielded the low temperature dependence of the magnetization and that of the ferromagnetic Curie temperature. Good agreement was obtained with available experimental results