Magnetoelectric properties of NiFe2O4/0.65BaTiO3-0.35Na0.5Bi0.5TiO3 bilayer thin films deposited via pulsed laser deposition

Lead-free magnetoelectric (ME) NiFe2O4/0.65BaTiO(3)-0.35Na(0.5)Bi(0.5)TiO(3) (NFO/BT-NBT) bilayer thin films grown on (001)-SrRuO3/SrTiO3 (SRO/STO) substrates were prepared via pulsed laser deposition. Different deposition sequences of the BT-NBT and NFO layers on the substrates yielded the following layered structures: NFO/BT-NBT/SRO/STO and BT-NBT/NFO/SRO/STO. Structural characterization via X-ray diffraction indicated that all of the samples are good crystallization and show c-axis orientation. Physical properties testing indicated that such heteroepitaxial composite thin films simultaneously exhibit excellent ferroelectric, dielectric, ferromagnetic, and ME coupling properties. Meanwhile, the ME coupling behavior of the bilayer thin films is influenced by growth sequences of the composite films. The ME coupling coefficient of the BT-NBT/NFO/SRO/STO (alpha(E) similar to 120 mV cm(-1) Oe(-1)) thin film is smaller than that of the NFO/BT-NBT/SRO/STO (alpha(E) similar to 140 mV cm(-1) Oe(-1)) thin film, which may be due to the different substrate clamping effect.