Magnetic nanoparticles: When atoms move around

The degree of atomic ordering in magnetic nanoparticles decreases strongly with the particles size is discussed. Excellent magnetic properties, a high-temperature annealing step is required to recover the atomic order. The researchers annealed disordered Fe (Co) or Pt (Pd) atoms (CoPt) nanoparticles at 500 °C for up to a maximum of 16 hour. When the nanoparticles become smaller, coordination at the surface is progressively reduced. The continuous disordering has been attributed to the surface-induced disorder related to platinum segregation onto the particle surface. It also presents some fresh perspectives for designing nanoparticles for industrial applications, such as ultrahigh-density magnetic-storage media.