Structure transition and improved multiferroic properties of Bi_1-xTb_xFeO₃ (x = 0.00-0.15) thin films

We investigated phase constitutions, ferroelectric, and magnetic characteristics of BFO films with Tb substitution. Bi _1-x Tb _x FeO ₃ (x = 0.00-0.15) thin film were prepared on the Pt buffered glass substrates by pulsed laser deposition. 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 ferroelectric and ferromagnetic properties at the same time. The remanent polarization (2P _r ) of 157 μC/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 Bi _0.95 Tb _0.05 FeO ₃ is due to the magnetic moment of the doped Tb ³⁺ ion in addition to the suppressed spiral spin configuration. The result of this work indicates that the radius and magnetic moment of the Tb ³⁺ ions play a critical role in the structural evolution, refined microstructure, and therefore enhanced multiferroic properties for Tb substituted BFO polycrystalline films.