Structural transformation and multiferroic properties of single-phase Bi _0.89 Tb _0.11 Fe _1-x Mn _x O ₃ thin films

Pure BiFeO ₃ (BFO) and Tb, Mn co-doped BiFeO ₃ (BTFMO) thin films were deposited on SnO ₂ : F (FTO)/glass substrates using a chemical solution deposition method. Detailed investigations were made on the influence of (Tb, Mn) co-doping on the structure change and the electric properties of the BFO films. With the co-doping of Tb and Mn, the structural transformation from rhombohedral R3c to triclinic P1 is confirmed through XRD, Rietveld refinement and Raman analysis. XPS analysis clarifies that (Tb, Mn) co-doping avails to decrease oxygen vacancy concentration, showing less Fe ²⁺ ions in the co-doped BTFMO thin films than that of the pure BFO thin film. Among the co-doped thin films, the BTFM ₁ O film shows the highly enhanced ferroelectric properties with a giant remnant polarization value (2P _r = 180.3 μC/cm ² ). The structural transformation, the well-distributed fine grains and the reduction of leakage current favor enhanced ferroelectric property of (Tb, Mn) co-doped BFO films. It is also found that the BTFM ₁ O film shows the enhanced ferromagnetism with the saturated magnetization (M _s = 2.5 emu/cm ³ ) as a result of the collapse of space modulated spin structure by the structure transformation.