Ferromagnetic ordering in nickel doped BiFeO3 nanostructured thin films

Abstract

The study has made on Ni-doped BiFeO3 (BFO) thin films principally its magnetic properties. BiFe1−xNixO3 (Ni = 0.025, 0.05, 0.075 and 0.10) films were synthesized by the indigenously developed novel hot-wall spray pyrolysis system. It is evidenced from field-emission scanning electron microscopy (FESEM) that Ni doping tremendously modified the shape of the particles from individual rod structure to grouped nanocrystalline grains. M–H curve reveals that Ni doping lead to increase in saturation magnetization and remanent magnetization values of BFO at room temperature (RT) and low temperature (LT). These changes are unveiled due to the structural disorder evidenced from Grazing Incidence X-ray Diffraction (GIXRD) and oxygen vacancy evidenced from X-ray photoelectron spectroscopy (XPS), which are responsible for the magnetic exchange interactions between Fe–O–Fe and Fe–O–Ni. The study of coercivity and blocking temperature with M–H and M–T curves showed that incorporation of Ni decreases the anisotropic energy and coercivity values. These results confirmed that Ni doping modifies the canting structure order which breaks the domains into multi-domains. High retentivity with optimum coercivity makes Ni doped BFO as a good soft magnetic material which finds applications in magnetic data storage devices.