Cobalt nanosized particles organized in a 2D superlattice: Synthesis, characterization, and magnetic properties

Colloidal assemblies are used to synthesize FCC cobalt nanoparticles. The particles are coated, extracted from micelles, and characterized by transmission electron microscopy, small angle X-ray scattering, and electron and X-ray diffraction spectroscopy. These cobalt metal particles are stable in air, have a narrow size distribution, and on deposition on a graphite support, spontaneously form a 2D hexagonal network. The magnetic properties are compared when they are dispersed in a solvent and organized in 2D superlattices. Changes in the hysteresis loop and in the blocking temperature are observed and attributed to collective flip of the magnetization of adjacent particles.