Crystallite Size Dependent Superparamagnetic Properties of Gold Doped Reduced Graphene Oxide Nanocomposite: An Experimental and Density Functional Theory Study

The current study focuses on the superparamagnetic properties of reduced graphene oxide achieved through varying the crystallite size of rGO nanosheet and incorporating gold nanoparticles (Au-NP). Superparamagnetic features were observed for rGO and Au-NP functionalized rGO (rGO: Au-NP) with corresponding low remanence and coercivity. The superparamagnetic features can be attributed to the crystallite sizes of rGO and rGO: Au-NP as evidenced from X-ray diffraction crystallite size analysis. Density functional theory calculations showed the formation of additional unoccupied states with a corresponding increase in spin density contributions from the hydroxyl functional group and Au atomic doping. The partial density of states revealed C-2p, O-2p, and Au-5d orbitals as the major contributors to the magnetic properties of rGO composites.