Surface effects in noninteracting and interacting g-Fe2O3 nanoparticles

From AC susceptibility, magnetization and Mössbauer spectroscopy measurements, we show the dominant role of the surface properties and surface-to-core exchange coupling on the static and dynamic properties of g-Fe2O3 particles (2.7, 4.6 and 8.7 nm) dispersed in a polymer or powdered. Measurements of the switching field of individual particles are presented, demonstrating basic surface effects.