Synthesis, structure, and magnetic studies on the CoFe2O4–BiFeO3 nanocomposite films with different number of CoFe2O4 layers

• CoFe2O4–BiFeO3 films have been successfully growned via the spin-coating process.
• CFO–BFO films exhibit better magnetic properties than the film contains only BFO.
• The microstructures of the films are analysed with HRTEM and SAED in detail.

The multiferroic heterostructures consisting of CoFe2O4 (CFO)–BiFeO3 (BFO) layers with increasing the number of CFO layers (2, 4, 6 and 8) have been grown on LaNiO3 buffered Si (1 0 0) substrate by a simple sol–gel spin-coating route. X-ray diffraction (XRD) shows that the CFO and BFO phases have been successfully retained in the heterostructures and the films are polycrystalline. The high resolution transmission electron microscope (HRTEM) images show the clear interplanar distances and the interface between the two phases. The magnetization (M) versus field (H) loops reveal that, with increasing the CFO layers, the magnetization of CFO–BFO films will be enhanced. The Ms, Mr and Hc of the composite film with 8 CFO layers are measured to be the largest values of 1304 emu/cm3, 562 emu/cm3 and 2074 Oe, respectively.