Low Dielectric Loss and Multiferroic Properties in Ferroelectric/Mutiferroic/Ferroelectric Sandwich Structured Thin Films

Bismuth ferrite (BiFeO₃) has proven to be promising for a wide variety of microelectric and magnetoelectric devices applications. In this work, a dense (Ba_0.65Sr_0.35)TiO₃(BST)/(Bi_0.875Nd_0.125)FeO₃(BNF)/BST trilayered thin film grown on Pt-coated Si (100) substrates was developed by the rf-sputtering. For comparison, single-layered BNF and BST were also prepared on the same substrates, respectively. The results show that the dielectric loses suppression in BST/BNF/BST trilayered thin films at room temperature but has enhanced ferromagnetic and ferroelectric properties. The remnant polarization (P_r) and coercive electronic field (E_c) were 5.51 μC/cm² and 18.3 kV/cm, and the remnant magnetization (M_r) and coercive magnetic field (H_c) were 10.1 emu/cm³ and 351 Oe, respectively, for the trilayered film. We considered that the bismuth’s volatilization was limited by BST bottom layers making the Bi/Fe in good station, and the action of BST layer in the charge transfer between BNF thin film and electrode led to the quite low leakage current and enhanced multiferroic property. The origin of the mechanism of the highly enhanced dielectric constant and decreased loss tanδ was discussed.