Electronic structure of bismuth ferrite and hematite single crystals: X-ray photoelectron study and calculation

The X-ray photoelectron spectra of the inner levels and valence bands of the surfaces of BiFeO 3 and Fe 2 O 3 single crystals have been measured using X-ray photoelectron spectroscopy on an ESCALAB 250 X-ray photoelectron microprobe with monochromatization of X-ray radiation of the Al K α line. The ab initio calculations have been performed by the full-potential pseudopotential method in terms of the density functional theory (Quantum-Espresso program package). The band structure and the total and partial densities of states have been calculated for the BiFeO 3 and Fe 2 O 3 systems. A comparison of the theoretical and experimental results has demonstrated good agreement between theory and experiment.