Photoemission and x-ray absorption of the electronic structure of multiferroicRMnO3(R=Y,Er)

Abstract

Electronic structures of multiferroic $R\mathrm{Mn}{\mathrm{O}}_{3}$ $(R=\mathrm{Y},\mathrm{Er})$ have been investigated by employing photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). We have found that Mn ions in $R\mathrm{Mn}{\mathrm{O}}_{3}$ are in the trivalent high-spin state with the total spin of $S=2$. The occupied Mn $({d}_{xz}\ensuremath{-}{d}_{yz})$ states lie deep below ${E}_{F}$, while the occupied Mn $({d}_{xy}\ensuremath{-}{d}_{{x}^{2}\ensuremath{-}{y}^{2}})$ states overlap very much with the O $2p$ states. It is observed that the PES spectral intensity of Mn $3d$ states is negligible above the occupied O $2p$ bands, suggesting that $\mathrm{Y}\mathrm{Mn}{\mathrm{O}}_{3}$ is likely to be a charge-transfer insulator. The Mn ${d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ state is mostly unoccupied in the ferroelectric phase of $\mathrm{Y}\mathrm{Mn}{\mathrm{O}}_{3}$.