The beta Phase of Multiferroic Bismuth Ferrite and its beta-gamma Metal-Insulator Transition

R. Palai; R. S. Katiyar; H. Schmid; P. Tissot; S. J. Clark; J. Robertson; S. A. T. Redfern; J. F. Scott

doi:10.1103/PhysRevB.77.014110

The beta Phase of Multiferroic Bismuth Ferrite and its beta-gamma Metal-Insulator Transition

Materials Science 2008-02-01 v3 Other Condensed Matter

Authors: R. Palai , R. S. Katiyar , H. Schmid , P. Tissot , S. J. Clark , J. Robertson , S. A. T. Redfern , J. F. Scott

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Abstract

We show that epitaxial (001) thin films of multiferroic bismuth ferrite BiFeO3 are monoclinic at room temperature instead of tetragonal or Rhombohedral as reported earlier . We report a orthorhombic order-disorder beta-phase between 820C and 950C contrary to the earlier report. The transition sequence monoclinic-orthorhombic phase in (001)BiFeO3 thin film (rhombohedral-orthorhombic transition in single crystal) resembles that of BaTiO3 or PbSc1/2Ta1/2O3. The transition to the cubic $\gamma$ -phase causes an abrupt collapse of the bandgap toward zero (insulator-metal transition) at the orthorhombic-cubic beta-gamma transition around 950C. This transition is similar to the metal-insulator transition in Ba0.6K0.4BiO3.

Keywords

bismuth ferrite multiferroics phase transition metal-insulator transition epitaxial thin films bandgap collapse

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@article{arxiv.0705.2883,
  title  = {The beta Phase of Multiferroic Bismuth Ferrite and its beta-gamma Metal-Insulator Transition},
  author = {R. Palai and R. S. Katiyar and H. Schmid and P. Tissot and S. J. Clark and J. Robertson and S. A. T. Redfern and J. F. Scott},
  journal= {arXiv preprint arXiv:0705.2883},
  year   = {2008}
}

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5 Pages, 5 grphs

The beta Phase of Multiferroic Bismuth Ferrite and its beta-gamma Metal-Insulator Transition

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