Size-dependent superparamagnetic properties of MgFe2O4 spinel ferrite nanocrystallites

Superparamagnetism is a unique and important aspect of magnetism in nanoparticles. The superparamagnetic properties of the MgFe2O4 spinel ferrite nanoparticles with the particle size from about 6 to 18 nm are studied. The blocking temperature is a function of the particle size and increases with increasing particle size. The coercivity of MgFe2O4 nanoparticles also is a function of the particle size below the blocking temperature. When the temperature rises above the blocking temperature, the nanoparticles show nonhysteresis magnetization behaviors. With these interesting superparamagnetic properties, MgFe2O4 nanoparticles have potentials for applications such as ferrofluids, magnetocaloric refrigeration, and the contrast agents for magnetic resonance imaging.