We demonstrate the microscopic role of oxygen vacancies spatially confined within nanometer inter-spacing (about 1 nm) in BiFeO3, using resonant soft X-ray scattering techniques and soft X-ray spectroscopy measurements. Such vacancy confinements and total number of vacancy are controlled by substitution of Ca2+ for Bi3+ cation. We found that by increasing the substitution, the in-plane orbital bands of Fe3+ cations are reconstructed without any redox reaction. It leads to a reduction of the hopping between Fe atoms, forming a localized valence band, in particular Fe 3d-electronic structure, around the Fermi level. This band localization causes to decrease the conductivity of the doped BiFeO3 system.
@article{arxiv.1508.02334,
title = {Orbital Reconstruction in a Self-assembled Oxygen Vacancy Nanostructure},
author = {H. Jang and G. Kerr and J. S. Lim and C. -H. Yang and C. -C. Kao and J. -S. Lee},
journal= {arXiv preprint arXiv:1508.02334},
year = {2015}
}