Magnetic order in amorphous nanoparticles of (Fe0.25Nd0.75)0.6B0.4

M. TORTAROLO; R. D. ZYSLER; H. ROMERO

Workshop; VII Latin American Workshop on Magnetism, Magnetic Materials and Their Applications; 2005

We are focusing in the internal order of (Fe0.25Nd0.75)0.6B0.4 nanoparticles in dispersed samples (weakly interacting system) as well as in powder samples (interacting system) in order  to understand both the influence of the internal  structure and the interactions among particles. The experimental characterisation of the cohercive field, the saturation magnetisation and the remanent magnetisation show a sharp increase below a certain temperature: 60 K for dispersed sample and 80 K for the powder one. We discus these results in the frame of a core-shell model which represents each particle as an ordered core plus an initially disordered shell that grows ordered as the temperature is lowered. Interparticle interaction effect in the magnetic order are also discussed.