XAFS investigation of the correlation of Bi-sublattice disorder with ferromagnetism of multiferroic BiFeO₃ nanoparticle

Effect of Mn and Ba Codoping on a Magnetic Spin Cycloid of Multiferroic Bismuth Ferrite Nanoparticles

“…Lahiri et al argued that disorder of nonmagnetic A-site cations can control the magnetism of BFO NPs . Doping of nonmagnetic alkaline-earth metal ions at the A-sites can suppress cycloidal spin modulation and improve magnetoelectric coupling without structural changes up to 25% of incorporation .…”

“…28 Lahiri et al argued that disorder of nonmagnetic A-site cations can control the magnetism of BFO NPs. 29 Doping of nonmagnetic alkaline-earth metal ions at the A-sites can suppress cycloidal spin modulation 30 and improve magnetoelectric coupling without structural changes up to 25% of incorporation. 31 B-site substitution directly affects the exchange interaction between B-site cations and has a strong impact on the magnetic properties, while the reduction of Fe 3+ to Fe 2+ can also be suppressed.…”

Low-Temperature Surface Phase Transitions in Multiferroic BiFeO3 Nanocrystals Probed via Electron Paramagnetic Resonance

“…Hence, the Bi−O disorder influences Fe− O − Fe, which in turn affects the DM superexchange interaction. 33,34 The milestone of this work, however, is its subtle focus on the topics, which are the prime focus to the multiferroic community:…”

“…Control of the particle size as an alternative to doping induced distortions. 33,34 From these investigations, it is clear that (i) BFO's skin layer is different from its bulk, (ii) there is a change in the lattice volume of the skin layers compared to the bulk BFO, (iii) the skin layers have different structural, electronic, and magnetic properties, and (iv) either simultaneously or individually, spin reorientations and hopping and settling of charges occur during these phase transitions.…”

“…The most important points to take away from this work are (i) as the BFO particle size becomes smaller, the BiO 6 cage undergoes large distortions, and consequently, the FeO 6 octahedra rotate, (ii) the Bi–O bond lengths in nano BFO increase significantly (bond length distributions Bulk σ BiO1 2 = 0.0047 Å 2 and Nano σ BiO1 2 = 0.0052 Å 2 , Bulk σ BiO2 2 = 0.009 Å 2 and Nano σ BiO2 2 = 0.0128 Å 2 ) with a minor disorder in the FeO 6 cage (σ FeO = 0.04 Å), which also influences the interunit Fe–Fe disorder (Δσ FeFe 2 ≈ 44%), and (iii) the sublattice distortions of BiO 6 and FeO 6 result in a change in the Fe–O–Fe bond angle (due to common O), wherein the ideal Fe–O–Fe angle changes from 154.8 to <133°. Hence, the Bi–O disorder influences Fe–O – Fe, which in turn affects the DM superexchange interaction. , The milestone of this work, however, is its subtle focus on the topics, which are the prime focus to the multiferroic community: By tuning the particle size of BFO, one may introduce topological ferromagnetism (FM shell–AFM core); Control of the particle size as an alternative to strain induced functional octahedral distortions for applications that require an amplified magnetoelectric effect; and Control of the particle size as an alternative to doping induced distortions. , …”