Interfacial Charge Induced Magnetoelectric Coupling at BiFeO₃/BaTiO₃ Bilayer Interface

Bilayer thin films of BiFeO3-BaTiO3 at different thicknesses of BiFeO3 were prepared by RF-magnetron sputtering technique. A pure phase polycrystalline growth of thin films was confirmed from XRD results. Significantly improved ferroelectric polarization (2Pr ∼ 30 μC/cm(2)) and magnetic moment (Ms ∼ 33 emu/cc) were observed at room temperature. Effect of ferroelectric polarization on current conduction across the interface has been explored. Accumulation and depletion of charges at the bilayer interface were analyzed by current-voltage measurements which were further confirmed from hysteretic dynamic resistance and capacitance voltage profiles. Magnetoelectric coupling due to induced charges at grain boundaries of bilayer interface was further investigated by room temperature magnetocapacitance analysis. A room temperature magnetocapacitance was found to originate from induced charge at the bilayer interface which can be manipulated by varying the thickness of BFO to obtain higher ME coupling coefficient. Dynamic magnetoelectric coupling was investigated, and maximum longitudinal magnetoelectric coupling was observed to be 61 mV/cm·Oe at 50 nm thickness of BiFeO3. The observed magnetoelectric properties are potentially useful for novel room temperature magnetoelectric and spintronic device applications.