Structure Transition and Improved Multiferroic Properties of Bi1−xTbxFeO3 (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
$157 ~\mu \text{C}$
/cm2 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/cm3 is found for
$x$
= 0.05 film. The enhanced
$M_{s}$
with Bi0.95Tb0.05FeO3 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 (MF) properties for Tb-substituted BFO polycrystalline films.