Surface anisotropy induced magnetism in BaTiO3-CoFe2O4 (BTO-CFO) nanocomposite

Nanocomposite of BaTiO3 (BTO) and CoFe2O4 (CFO) exhibits magnetism which can be explained by assuming the surface interaction between BTO and CFO. The crystal phase of the nanocomposite has been studied by the X-ray diffraction (XRD) technique which has been supported by the Raman spectra analysis. Surface morphology has been studied using SEM (scanning electron microscopy) and TEM (Transmission electron microscopy). The ball milling has transformed diamagnetic microcrystalline of BTO to nanocrystal ferromagnetic BTO which could be due to oxygen vacancies at the surface of BTO. Thus there has been ferromagnetic exchange interaction between nanocrystalline BTO and CFO at their interfaces which ultimately affect the spin arrangement at the surface of CFO. This interaction leads to high saturation magnetization. A hump in the M-H loop at around ±4000 Oe has been observed for the BTO-CFO composites. It changes its shape with the increase in concentration of CFO. It is probably due to increase of superexchange interaction between CFO and BTO at the interface.