Effects of Ti and Mn Co-substitution on P4mm BiFeO3: An Ab Initio Calculation

• Published in: Journal of superconductivity and novel magnetism 2017-09, Vol.30 (9), p.2471-2479
• Main Authors: Zhang, Ren, Zhou, Yunhua, Zhu, Yiyi, Li, Yangyang, Chu, Liang, Min, Yonggang, Zhang, Jian, Yang, Jianping, Li, Xing’ao
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Magnetic Materials; Magnetism; Original Paper; Physics; Physics and Astronomy; Strongly Correlated Systems; Superconductivity
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-017-4048-y

Tetragonal BiFeO 3 (BFO), which has a giant spontaneous polarization, has attracted a great deal of attention recently. In this paper, we systematically study the structural, magnetic, electronic and optic properties of BFO, BiFe 0.75 Mn 0.25 O 3 (BFMM), and BiFe 0.75 Ti 0.125 Mn 0.125 O 3 (BFMT). Results show that doping Ti and Mn into the Fe sites increases the c / a ratio and enhances the magnetization of BiFeO 3 from 0 to 5 μ B . The crystal symmetry changes from orthogonality to tetragonality with half of the Mn atoms being replaced by Ti in BiFe 0.75 Mn 0.25 O 3 , which suppresses the energy splitting of the Mn 3d orbitals and thus enlarge the band gap to 1.21 eV for BiFe 0.75 Ti 0.125 Mn 0.125 O 3 . Our calculated Bader charge and charge density difference show that the smallest volume of BiFe 0.75 Mn 0.25 O 3 arises from the strong Mn–O bonds in BiFe 0.75 Mn 0.25 O 3 . Further investigations indicate similar optical behaviors for BiFeO 3 and BiFe 0.75 Ti 0.125 Mn 0.125 O 3 . However, BiFe 0.75 Mn 0.25 O 3 exhibits strong absorption in the infrared region for the transition from O 2p to Mn e g 2 and t 2 g 3 .