Synthesis and magnetic properties of CoFe2O4 and MnFe2O4 nano composites

Highly dispersed granular nano-composite material of CoFe2O4 and MnFe2O4 with an average size of 20 nm is synthesized through thermal decomposition. The soft-hard magnet exchange-spring effect is observed in magnetization measurements at low temperatures, and is found to be strongly affected by the temperature of the reaction and the composition ratio between soft and hard magnetic phases. Magnetization measurements at different temperatures show that at 20 K, the saturation magnetization increases significantly, which is attributed to the freezing of the spin-glass like state at the surface of the nano-composite material. A Henkel Plot measurement on our sample shows that for the dispersed composite material of CoFe2O4 and MnFe2O4, the dipole interaction is dominant among magnetic interactions.