Theory of Raman and Resonant Inelastic X-ray Scattering from Collective Orbital Excitations in YTiO${}_3$

Abstract

We present two different theories for Raman scattering and Resonant Inelastic X-ray Scattering (RIXS) in the low temperature ferromagnetic phase of YTiO${}_3$ and compare this to the available experimental data. For description of the orbital ground-state and orbital excitations, we consider two models corresponding to two theoretical limits: one where the $t_{2g}$ orbitals are degenerate, and the other where strong lattice distortions split them. In the former model the orbitals interact through superexchange. The resulting superexchange Hamiltonian yields an orbitally ordered ground state with collective orbital excitations on top of it - the orbitons. In the orbital-lattice model, on the other hand, distortions lead to local dd-transitions between crystal field levels. Correspondingly, the orbital response functions that determine Raman and RIXS lineshapes and intensities are of cooperative or single-ion character. We find that the superexchange model yields theoretical Raman and RIXS spectra that fit very well to the experimental data.

Summary of changes: 1) Calculation of Raman spectrum in local model added. 2) RIXS treatment is generalized, the Ultrashort Core hole Lifetime is no longer needed. The RIXS sections are rearranged

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Cited by in corpus (8)

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• Magnetic anisotropy in the Kitaev model systems Na2IrO3 and RuCl3
• Resonant inelastic x-ray scattering operators for $t_{2g}$ orbital systems
• Orbital superexchange and crystal field simultaneously at play in YVO3: resonant inelastic x-ray scattering at the V L edge and the O K edge
• Structural and metal-insulator transitions in rhenium based double perovskites via orbital ordering
• Spin-orbital excitation continuum and anomalous electron-phonon interaction in the Mott insulator LaTiO${}_3$
• Dynamics of a j=3/2 quantum spin liquid
• Resonant inelastic x-ray scattering study of vector chiral ordered kagome antiferromagnet