Electronic structures of alpha -Fe2O3 and Fe3O4 from O K-edge absorption and emission spectroscopy.

Abstract

We present O K-edge absorption and emission spectra for \ensuremath{\alpha}-${\mathrm{Fe}}_{2}$${\mathrm{O}}_{3}$ and ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$ obtained using a high-resolution-undulator soft-x-ray radiation source. The occupied and the unoccupied O p densities of states are obtained and compared with the valence-band photoemission results. While these results confirm that \ensuremath{\alpha}-${\mathrm{Fe}}_{2}$${\mathrm{O}}_{3}$ can be classified as a charge transfer or an intermediate-type insulator, they suggest that ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$ is more likely of the Mott-Hubbard type. The excitation-energy dependence of the emission spectra is also discussed.