Giant magnetoelectric coupling interaction in BaTiO3/BiFeO3/BaTiO3 trilayer multiferroic heterostructures

Multiferroic trilayer thin films of BaTiO3/BiFeO3/BaTiO3 were prepared by RF-magnetron sputtering technique at different thicknesses of BiFeO3 layer. A pure phase polycrystalline growth of thin films was confirmed from X-ray diffraction results. The film showed maximum remnant electric polarization (2Pr) of 13.5 μC/cm2 and saturation magnetization (Ms) of 61 emu/cc at room temperature. Thermally activated charge transport dominated via oxygen vacancies as calculated by their activation energy, which was consistent with current–voltage characteristics. Magnetic field induced large change in resistance and capacitance of grain, and grain boundary was modeled by combined impedance and modulus spectroscopy in the presence of varied magnetic fields. Presence of large intrinsic magnetoelectric coupling was established by a maximum 20% increase in grain capacitance (Cg) with applied magnetic field (2 kG) on trilayer having 20 nm BiFeO3 layer. Substantially higher magnetoelectric coupling in thinner films has bee...