Multiferroic and fatigue behavior of BiFe0.95Mn0.05O3/Bi0.90La0.10Fe0.85Zn0.15O3 bilayered thin films

Bilayered thin films consisting of BiFe_0.95Mn_0.05O₃ (BFMO) and Bi_0.90La_0.10Fe_0.85Zn_0.15O3 (BLFZO) layers were prepared on Pt-coated silicon substrates without any buffer layers by RF sputtering. The (110) orientation was induced with a high phase purity for all bilayers as a result of the introduction of the bottom (110)-oriented BLFZO layer. The low leakage current density of BFMO/BLFZO bilayers could be attributed to a combined effect of the BFMO and BLFZO layers. The dielectric constant increases, the remanent polarization decreases, and the coercive field slightly increases with increasing thickness of the BLFZO layer in BFMO/BLFZO bilayers. Magnetic properties in BFMO/BLFZO bilayers are improved by increasing the BFMO layer thicknesses. A large polarization value of 2P_r ~ 189.5 μC/cm² is obtained for the BFMO/BLFZO bilayer with a thickness ratio of 3:1, which is much larger than those reported for BFO-based single layers or multilayers, and a good fatigue behavior is demonstrated with an increase in measurement frequencies and driving electric fields.