Variations of ferroelectric off-centering distortion and 3d-4p orbital mixing in La-doped BiFeO3 multiferroics

Jung Hoon Lee, Hyoung Joon Choi, Dongeun Lee, Min G. Kim, Chung W. Bark, Sangwoo Ryu, Min Ae Oak, Hyun Myung Jang

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Abstract

The lanthanum (La) modification is known to improve dielectric and magnetic properties of BiFeO3 (BFO), a promising room-temperature multiferroic oxide. The effects of La doping on the variations of the off-centering distortion and the orbital mixing of BFO are experimentally studied, in conjunction with first-principles density-functional theory (DFT) calculations. Both the Fe-O bond anisotropy in the FeO6 -octahedron cage and the off-centering ferroelectric polarization along the hexagonal [001] h are predicted to be substantially reduced by the La doping. These DFT predictions agree with the structural-refinement results obtained from high-resolution x-ray powder-diffraction data. We have shown that the apparent improvement of the polarization-field response is not intrinsic and can be attributed to the reduced leakage current by the La doping. X-ray absorption near-edge structure (XANES) spectroscopy study further indicates that the degree of Fe3d-4p orbital mixing decreases with the La doping. The conclusion deduced from XANES study correlates well with the orbital-resolved density of states which predicts that the La doping increases the number of unoccupied states in the p orbital but suppresses the number of unoccupied states in the Fe3d orbital.

Original languageEnglish
Article number045113
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume82
Issue number4
DOIs
Publication statusPublished - 2010 Jul 16

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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