Magnetoelectric effect in multiferroic heteroepitaxial BaTiO3–NiFe2O4 composite thin films

Abstract Heterostructured NiFe 2 O 4 –BaTiO 3 composite thin films epitaxially grown on (1 1 1)-SrTiO 3 single-crystal substrate were prepared using pulsed-laser deposition, where the BaTiO 3 layer grew as columnar structure while the NiFe 2 O 4 layer formed a continuous film. Structural characterization by X-ray diffraction and electron microscopy showed good horizontal heterostructures of (1 1 1)-oriented BaTiO 3 and (1 1 1)-oriented NiFe 2 O 4 on (1 1 1)-SrTiO 3 whatever their deposition sequences. Such heterostructures present simultaneously strong ferroelectric and ferromagnetic responses at room temperature. In particular, an obvious direct magnetoelectric coupling effect was observed in the heterostructured films. The growth sequence of the BaTiO 3 and NiFe 2 O 4 layers on the substrate has an effect on multiferroic behavior of the composite thin films.