Ferromagnetic exchange interaction and Curie temperature of Mg1+xFe2-2xTixO4 (x=0-0.5) system

The thermo-magnetization curve, magnetic susceptibility at high temperatures, and X-ray diffraction measurement for water-quenched and slow-cooled Mg1+xFe2-2xTixO4 samples were measured. The magnetic exchange interaction J(AB) between A- and B-sites in the inverse spinet structure and Curie temperature were evaluated, using Rietveld analysis and fitting the susceptibility to molecular field theory. The Curie temperature estimated was in good agreement with experimental data, except for a slight upper deviation of calculated T-c. The deviation might come from the correlation between J(AB) and angle phi of Fe-O-Fe ions. (c) 2006 Elsevier B.V. All rights reserved.