Magnetic interactions in graphene decorated with iron oxide nanoparticles

We present the studies of structural and magnetic properties of graphene composites prepared with several quantities ofα-Fe₂O₃dopant of 5%, 25% and 50% made with either ethanol or acetone. Our studies showed the presence of a weak magnetic order up to room temperature and saturation magnetization close to 0.2 emu g^-1in pure commercial graphene. With regard to magnetic properties of our graphene + iron oxide samples, the solvent used during the preparation of the composite had a significant influence on them. For graphene + Fe₂O₃samples made with acetone the magnetic properties of pure graphene played a major role in the overall magnetic susceptibility and magnetization. On the other hand, for graphene + iron oxide samples made with ethanol we observed the presence of superparamagnetic blocking atT < 110 K which was due to the additional appearance ofγ-Fe₃O₄nanoparticles. Changes in the synthesis solvent played a major role in the magnetic properties of our graphene + Fe₂O₃nanocomposite samples resulting in much higher saturation magnetization for the samples made with ethanol. Both the shape and the parameters characterizing magnetization hysteresis loops depend strongly on the amount of iron oxide and changes in the preparation method.