Synthesis and magnetic properties of hard-soft SRFe10Al2O19/NiZnFe2O4 ferrite nanocomposites

Pure phase exchange-coupled nanocomposites of hard-soft magnetic oxides, (hard) SrFe10Al2O19(-) (soft) Ni0.75Zn0.25Fe2O4 were prepared via autocombution method. Magnetic properties of the nanocomposites were assessed as a function of soft-phase content in the nanocomposite. A 40% increase in M(s) value was observed for nanocomposite with 30 Wt.% of the soft phase. A linear increase in M(r)/M(s) with soft-phase content indicates the presence of enhanced exchange-coupling between hard and soft phases of the nanocomposite. The highest M(r)/M(s) ratio of 0.68 was obtained for nanocomposite containing 30 Wt.% of the soft-phase. The observed reduction in coercieve field values of the nanocomposite with increase in soft-phase content is explained on the basis of competition between exchange and dipolar interaction between hard-soft and soft-soft phases of the nanocomposite.