X-ray emission and photoelectron spectra ofPr0.5Sr0.5MnO3

Abstract

The results of measurements of x-ray photoelectron (XPS), x-ray emission (XES), and x-ray absorption spectra and local spin-density approximation band structure (LSDA) calculations of ${\mathrm{Pr}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3}$ are presented. The excitation energy dependence of Mn ${L}_{2,3}$ and O $K\ensuremath{\alpha}$ x-ray emission spectra of ${\mathrm{Pr}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3}$ is measured using tunable synchrotron radiation. The XES measurements yielded no photon energy dependence for the O $K\ensuremath{\alpha}$ spectra, but the Mn ${L}_{2,3}$ spectra yielded inelastic scattering losses of 2 and 6 eV, corresponding to features in the structure of the occupied part of the valence band. Comparing XPS and XES measurements with LSDA band-structure calculations, one concludes that the electronic structure of the compound consists mainly of Mn $3d$ and O $2p$ states. States of $3d$ character localized at the Mn site predominate near the top of the valence band (VB). Some differences in the Mn $3d$ distribution in this part of the XPS valence band and Mn ${L}_{3}$ XES with d symmetry due to spin-selection rules that govern the Mn ${L}_{3}$ XES. In addition, the Mn $3d$ states distribution is hybridized with the O $2p$ part of the VB. Mn ${L}_{3}$ XES spectra were determined relative to the Fermi energy by assuming normal x-ray emission begins from the lowest level of the ${p}^{5}{d}^{n+1}L$ intermediate state (which is the Mn $2p$ ionizatation threshold). From the local spin-density approximation, the orbital character of the Mn $3d$ electrons can be assigned ${e}_{g}$ symmetry at the top of the valence band ${T}_{2g}$ in the central part of the VB, and equal contributions of ${e}_{g}$ and ${t}_{2g}$ states at the bottom of the valence band.