We report the valence-to-core resonant inelastic x-ray scattering of EuS measured at the L_{3} edge of Eu. The obtained data reveal two sets of excitations: one set is composed of a hole in the S 3p bands and an electron excited to extended Eu 5d band states, and the other is made up from a hole in the Eu 4f states and an electron in localized Eu 5d states bound to the 4f hole by its Coulomb potential. The delocalized excitations arise from the dipole-allowed 5d→2p emissions, whereas the localized excitations result from the dipole-forbidden (quadrupole-allowed) 4f→2p emissions. Both these emission channels have a comparable intensity thanks to a small number of occupied 5d states (≈0.6) combined with a large number of occupied 4f states (seven). We identify the localized electron-hole pairs with the "magnetic excitons" suggested in the past as an interpretation of the sharp features seen in the optical absorption spectra. Our observations provide a direct experimental evidence of these excitons, which has been missing up to now.

Antwerp Maritime Academy Ghent University LumiLab Department of Solid State Sciences Krijgslaan 281 S1 B 9000 Gent Belgium and Noordkasteel Oost 6 Antwerp 2030 Belgium

ESRF The European Synchrotron 71 Avenue des Martyrs 38000 Grenoble France

Helmholtz Zentrum Dresden Rossendorf at the 71 Avenue des Martyrs Grenoble 38043 France and Institute of Resource Ecology Bautzner Landstraße 400 01328 Dresden Germany

Institute of Physics Czech Academy of Sciences Na Slovance 2 182 00 Prague Czech Republic

Citace poskytuje Crossref.org