Structure Transition and Improved Multiferroic Properties of Bi_1-xTb_xFeO₃ (x=0.00-0.15) Thin Films

We investigated phase constitutions, ferroelectric (FE), and magnetic characteristics of BiFeO3 (BFO) films with Tb substitution. Bi1-xTbxFeO3 (BTFO) (x = 0.00-0.15) thin films were prepared on the Pt-buffered glass substrates by pulsed laser deposition (PLD). BTFO films with x = 0.00-0.15 were confirmed to mainly consist of the perovskite phase. The structure in the studied films is transformed from rhombohedral for x = 0.00 to pseudo-cubic for x = 0.05-0.10, and orthorhombic for x = 0.15. The studied BTFO polycrystalline films exhibit the desired FE and ferromagnetic properties at the same time. The remanent polarization (2P(r)) of 157 mu C/cm(2) and electrical coercive field (E-c) of 485 kV/cm are obtained for BTFO films at x = 0.05. Besides, the saturation magnetization (M-s) of 15.0 emu/cm(3) is found for x = 0.05 film. The enhanced M-s with Bi0.95Tb0.05FeO3 is due to the magnetic moment of the doped Tb3+ ion in addition to the suppressed spiral spin configuration. The result of this work indicates that the radius and magnetic moment of the Tb3+ ions play a critical role in the structural evolution, refined microstructure, and therefore, enhanced multiferroic (MF) properties for Tb-substituted BFO polycrystalline films.