Influence of the thickness of BiFeO3 on the ferromagnet properties of layered multiferroic CoFe2O4–BiFeO3 films

Multiferroic layered films consisting of CoFe2O4–BiFeO3 (CFO–BFO) with increasing the thickness of BFO layer have been prepared on the LaNiO3 (LNO)-buffered Si (1 0 0) substrate via a simple spin-coating process. The thickness effects of BFO layer on the magnetic properties of CFO–BFO films have been investigated in detail. The X-ray diffraction results testify that magnetic CFO and ferroelectric BFO phases coexist in the heterostructured films. The HRTEM images show the well-defined microstructure of the CFO layer on LNO buffer. The magnetic measurement reveal that, with increasing the BFO thickness, the Ms of CFO–BFO films will be enhanced due to the stress. The film with 400 nm thickness BFO layers demonstrates the highest Ms value of 230 emu/cm3, which exhibits 137.1% enhancement than that of the film without BFO layers.

► CoFe2O4–BiFeO3 films have been successfully prepared via a simple spin-coating process.
► The CFO–BFO films exhibit better magnetic properties than the film contains only CFO layer.
► The microstructure of the CFO layer on the substrate is analyzed with HRTEM in detail.