Ferromagnetic, ferroelectric, and fatigue behavior of (111)-oriented BiFeO3 / (Bi1/2 Na1/2) TiO3 lead-free bilayered thin films

Abstract

Lead-free bilayered thin films consisting of BiFeO3 (BFO) and (Bi1/2 Na1/2) TiO3 (BNT) nanolayers were deposited on the Pt/ TiO2 / SiO2 /Si substrate by radio frequency sputtering. The bilayered BFO/BNT film exhibits a strong (111) orientation and much enhanced ferroelectric and magnetic properties (2 Pr =52.2 μC/ cm2, 2 Ec =554.0 kV/cm, 2 Ms =96.0 emu/ cm3, and 2 Hc =253.2 Oe) as compared to those of the single layer BNT and BFO thin films, together with an almost fatigue-free polarization behavior. Although space charges occur at the interface between the constituent nanolayers, as confirmed by the frequency dispersion of capacitance, the bottom BNT nanolayer appears to promote the growth and crystallization of BFO layer, largely responsible for the observed ferroelectric and magnetic behavior. © 2009 American Institute of Physics.