# Orbital Reconstruction in a Self-assembled Oxygen Vacancy Nanostructure

## TL;DR

Researchers found that oxygen vacancies in a specific material can change electronic structures and reduce conductivity without chemical reactions.

## Contribution

The study reveals orbital reconstruction in BiFeO3 due to oxygen vacancies without redox reactions.

## Key findings

- Oxygen vacancies in BiFeO3 lead to in-plane orbital band reconstruction of Fe3+.
- Localized valence bands form around the Fermi level, reducing conductivity.
- Substitution of Ca2+ for Bi3+ controls vacancy confinement and electronic structure.

## Abstract

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.