Magnetization behaviors of Fe3O4 nanoparticles studied by frequency-modulated magnetic force microscopy

Fe3O4 nanoparticles were synthesized through a sol-gel method. The structure and morphology features of the nanoparticles were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), and high resolution magnetic force microscopy (HR-MFM). The magnetization behaviors of Fe3O4 nanoparticles were investigated by using the frequency-modulated magnetic force microscopy (FM-MFM). It was observed that the prepared individual nanoparticles were within 20 nm. The high resolution amplitude and phase images of the nanoparticles were obtained separately by using the FM-MFM technique with an AC magnetic field. The magnetic distribution of the individual nanoparticles (~20 nm) was demonstrated by this technique.