Magnetic properties of Co₃O₄ nanoparticles on graphene substrate

Antiferromagnetic nanoparticles have attracted tremendous research interests due to the exhibiting magnetization reversal by quantum tunneling. However, the magnetic properties vary with the inter-particle separation owing to the strong magnetostatic interaction. Thus, a suitable synthetic method is needed to make the antiferromagnetic nanoparticles well-dispersed. Here a facile low-temperature hydrothermal method was used to fabricate the graphene-Co₃O₄ nanocomposites. The Co₃O₄ antiferromagnetic nanoparticles have a monodispersed grain size and anchor uniformly on the graphene surface. Compared with the pure Co₃O₄ nanoparticles with the similar size distribution, the graphene-Co₃O₄ nanocomposites present different magnetic properties, including the higher magnetization and the lower blocking temperature. It is deduced that the graphene matrix prevents the aggregation of Co₃O₄ nanoparticles which leads to the differences of magnetic properties.