Abstract
Mn3d valence states and elementary electronic excitations in single-crystalline TbMnO 3 were probed with resonant inelastic x-ray scattering (RIXS) (or resonant x-ray emission spectroscopy, RXES), polarized x-ray absorption spectra and ab initio electron-structure calculations. Polarized MnK -edge x-ray absorption spectra of TbMnO 3 crystals exhibit a significant anisotropy along three crystallographic directions, particularly for the white-line region. The 1s3p -RXES spectra obtained at the MnK edge reveal that the quadrupolar Raman regime is restricted predominantly to below the pre-edge peak whereas the fluorescence regime starts from the first pre-edge peak of 1s→3d transitions, indicating a relatively delocalized character of unoccupied Mn3d states. The additional Kβ emission profile at energy loss ∼62 eV is attributed to the off-site dipole Mn1s -Mn ′ 3d and/or Mn1s-Tb5d transitions, originating from hybridization between Mn4p states and neighboring Mn ′ 3d/Tb5d states. The off-site dipole transition makes a considerable contribution to the pre-edge region of MnK -edge spectrum. Three prominent RIXS features at ∼2.9, 7, and 11 eV were observed. Based on GGA+U calculations, the 7 eV region corresponds to transitions from O2p states to unoccupied minority Mn3d states, whereas the 11 eV band is ascribed to transitions from the O2p band to the empty Tb5d band. The broad 2.9 eV band is attributed to the coexistence of on-site Mn3d-Mn3d and off-site Mn3d -Mn ′ 3d transitions. © 2010 The American Physical Society.