Effect of annealing temperature on the structural and magnetic properties of nanocomposites of Cobalt Ferrite and Multi-layer Graphene

Graphene has emerged as a favorite research material for various technological applications. Pristine graphene is a diamagnetic material because of the delocalized π-bonding network. Nanocomposites of graphene with other ferromagnetic materials such as cobalt ferrite reflects multi-functional properties useful for storage devices, sensors, and photocatalytic applications. Nanoparticles of anisotropic diamagnetic multi-layer graphene (MLG) and ferrimagnetic CoFe₂O₄ (CFO) were synthesized through a one-step sonication process in the presence of a surfactant. The particle size, crystal structure, and magnetic properties of as synthesized nanocomposite were investigated by X-Ray Diffractometer (XRD), Atomic Force Microscopy (AFM), Magnetic Force Microscopy (MFM), Scanning Electron Microscopy (SEM), and Vibrating Sample Magnetometer (VSM). The nanocomposite presented a super-paramagnetic behavior. The saturation magnetization increased significantly with increased annealing temperature as a result of improved crystallinity. The saturation magnetization (M_s) at 400 ^oC annealing temperature observed was 400 emu/g. A trifold increase was observed for M_s (1200 emu/g) at 600 ^oC.