paper

Resonant Inelastic X-ray Scattering Study of Ca $_{3}$ Ru $_{2}$ O $_{7}$

arXiv:2004.13391 · doi:10.1103/PhysRevB.102.235104

Abstract

We present a combined oxygen $K$ -edge x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS) study of the bilayer ruthenate Ca $_{3}$ Ru $_{2}$ O $_{7}$ . Our RIXS experiments on Ca $_{3}$ Ru $_{2}$ O $_{7}$ were carried out on the overlapping planar and inter-planar oxygen resonances, which are distinguishable from the apical one. Comparison to equivalent oxygen $K$ -edge spectra recorded on band-Mott insulating Ca $_{2}$ RuO $_{4}$ is made. In contrast to Ca $_{2}$ RuO $_{4}$ spectra, which contain excitations linked to Mott physics, Ca $_{3}$ Ru $_{2}$ O $_{7}$ spectra feature only intra- $t_{2 g}$ ones that do not directly involve the Coulomb energy scale. As found in Ca $_{2}$ RuO $_{4}$ , we resolve two intra- $t_{2 g}$ excitations in Ca $_{3}$ Ru $_{2}$ O $_{7}$ . Moreover, the lowest lying excitation in Ca $_{3}$ Ru $_{2}$ O $_{7}$ shows a significant dispersion, revealing a collective character differently from what is observed in Ca $_{2}$ RuO $_{4}$ . Theoretical modelling supports the interpretation of this lowest energy excitation in Ca $_{3}$ Ru $_{2}$ O $_{7}$ as a magnetic transverse mode with multi-particle character, whereas the corresponding excitation in Ca $_{2}$ RuO $_{4}$ is assigned to combined longitudinal and transverse spin modes. These fundamental differences are discussed in terms of the inequivalent magnetic ground-state manifestations in Ca $_{2}$ RuO $_{4}$ and Ca $_{3}$ Ru $_{2}$ O $_{7}$ .

11 pages, 6 figures. This manuscript has been submitted to PRB

Resonant Inelastic X-ray Scattering Study of Ca3​Ru2​O7​

Abstract

Resonant Inelastic X-ray Scattering Study of Ca $_{3}$ Ru $_{2}$ O $_{7}$