Abstract
We present a combined oxygen -edge x-ray absorption spectroscopy and resonant inelastic x-ray scattering (RIXS) study of the bilayer ruthenate . Our RIXS experiments on were carried out on the overlapping planar and interplanar oxygen resonances, which are distinguishable from the apical one. Comparison to equivalent oxygen -edge spectra recorded on band-Mott insulating is made. In contrast to spectra, which contain excitations linked to Mott physics, spectra feature only intra- ones that do not directly involve the Coulomb energy scale. As found in , we resolve two intra- excitations in . Moreover, the lowest lying excitation in shows a significant dispersion, revealing a collective character different from what is observed in . Theoretical modeling supports the interpretation of this lowest energy excitation in as a magnetic transverse mode with multiparticle character, whereas the corresponding excitation in is assigned to combined longitudinal and transverse spin modes. These fundamental differences are discussed in terms of the inequivalent magnetic ground-state manifestations in and .
- Received 27 April 2020
- Revised 5 August 2020
- Accepted 11 November 2020
DOI:https://doi.org/10.1103/PhysRevB.102.235104
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