Ferroelectric properties of BiFeO3 thin films by Sr/Gd/Mn/Co multi-doping

Dielectric, Ferroelectric, and Magnetic Properties of Sm-Doped BiFeO3 Ceramics Prepared by a Modified Solid-State-Reaction Method

“…The coercive field (H c ) of the Sm8 sample is 0.8 kOe. The observation of the remnant magnetization in the doped BFO is believed to be due to the collapse the space modulated antiferromagnetic spin structure [4,10,11,12,13,14,15,16,17,18,19,20,21,22]. Pure BFO shows a magnetic cycloidal spiral structure (G-type antiferromagnetic ordering of Fe 3+ ions) with a long period of 620 ± 20 Å [37] and the remnant magnetization is zero due to the cancellation of the space-modulated magnetic spins.…”

“…This is because for the magnetoferroelectric (ME) applications, the Mr is a must for the ME coupling to occur [3,10,11,12,13,14,15]. The usual way to produce Mr in BFO material is by doping another cation at the Bi 3+ site, either magnetically-active ions (Nd, Sm, Gd, Tb, Mn, Ni, Co) or non-magnetically-active ions (La, Ca, Sr, Ba, Pb, Pd, Ti, Al, Zn) [14,15,16,17,18,19,20,21,22]. The remnant magnetization can also be induced by doping at the Fe 3+ site.…”

Enhanced Magnetic Properties of BiFeO3 Thin Films by Doping: Analysis of Structure and Morphology

“…After doping Mn 2+ ions, it can be found that the reduction of the A 1 modes and enhancement of the E modes in BFMO thin film. The variety of E modes can be regarded as the bending and stretching of FeO 6 octahedra [ 30 ]. In addition, the Raman scattering spectra in the vicinity of 624 cm −1 is changed significantly in E mode, which is related to the altered of Fe–O bonds induced by doping Mn 2+ ions [ 30 ].…”

“…The variety of E modes can be regarded as the bending and stretching of FeO 6 octahedra [ 30 ]. In addition, the Raman scattering spectra in the vicinity of 624 cm −1 is changed significantly in E mode, which is related to the altered of Fe–O bonds induced by doping Mn 2+ ions [ 30 ]. This result is in accordance with the reduced lattice parameter c in BFMO thin film of Figure 2 d. In our samples, XRD data is supported due to the absence of Raman mode of the impurity phases.…”

“…Above all, the coexistence of Fe 3+ and Mn 2+ ions causes a ferromagnetic Fe 3+ –O 2− –Mn 2+ super-exchange interaction [ 13 , 28 ]. This mechanism has three main influencing factors: the Fe 3+ –O 2− –Mn 2+ distance, the number of Fe 3+ –Mn 2+ magnetic ion pairs and the number of oxygen ions as the Fe 3+ –O 2− –Mn 2+ interaction medium [ 30 ]. As approved by XPS, the concentration of Fe 3+ ions increases with the Ho and Mn co-doping, while the concentration of oxygen vacancies is just the opposite.…”