Magnetic properties of Fe nanoparticle systems

The structure and magnetic properties of two systems of Fe-nanoparticles have been studied: (i) aerosol particles produced by a fast evaporation method and (ii) as-prepared particles dispersed in a silica aerogel matrix. The magnetic behavior of both samples is dominated by the long-range dipolar interparticle interactions but the confinement of Fe particle agglomerates in silica pores results in an enhancement of thermal fluctuation effects leading to a reduction of the remanence and coercivity.