Induced ferromagnetism in multilayered graphene in proximity with CoFe2O4

Abstract

Composites of anisotropic diamagnetic multilayer Graphene (MLG) and ferrimagnetic CoFe2O4 (CFO) nanoparticles (NPs) were synthesized through a one-step sonication process in the presence of a surfactant. The samples were characterized at ambient using x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, magnetic force microscopy (MFM) and magnetometry (vibrating sample magnetometer). An induced ferromagnetism was observed in MLG with saturation magnetization MS = 18 emu/g(MLG). This induced ferromagnetism is attributed to ferrimagnetic CFO uniformly distributed on the surface of diamagnetic MLG. SEM images confirm uniform dense distribution of CFO nanoparticles on MLG. MFM images confirm the formation of larger magnetic domains in the composite sample of MLG/CFO. The measured coercivity HC = 3.6 Oe of MLG/CFO composite is much smaller than HC = 32.4 Oe of pristine CFO NPs; this difference in HC is attributed to the effect of change in surface anisotropy.