Investigation of magnetic properties of interacting Fe2O3 nanoparticles

The magnetic properties of Fe2O3nanoparticles (average diameter H+3 nm) in alumina (68% Fe2O3in weight) have been investigated by magnetization measurements. The results indicate a superparamagnetic behavior of interacting particles, which block with decreasing temperature (the zero-"eld-cooled susceptibility shows a maximum at +145 K) with a distribution of relaxation times. A change of magnetic regime is observed below&60 K, due to the increasing interparticle interactions and local surface anisotropy