Non-local features of the spin-orbit exciton in Kitaev materials

Abstract

A comparative resonant inelastic x-ray scattering (RIXS) study of three well-known Kitaev materials is presented: $\alpha$-Li${}_2$IrO${}_3$, Na${}_2$IrO${}_3$, and $\alpha$-RuCl${}_3$. Despite similar low-energy physics, these materials show distinct electronic properties, such as the large difference in the size of the charge gap. The RIXS spectra of the spin-orbit exciton for these materials show remarkably similar three-peak features, including sharp low energy peak (peak A) as well as transitions between $j_{\text{eff}}=1/2$ and $j_{\text{eff}}=3/2$ states. Comparison of experimental spectra with cluster calculations reveals that the observed three-peak structure reflects the significant role that non-local physics plays in the electronic structure of these materials. In particular, the low-energy peak A arises from a holon-doublon pair rather than a conventional particle-hole exciton as proposed earlier. Our study suggests that while spin-orbit assisted Mott insulator is still the best description for these materials, electron itinerancy cannot be ignored when formulating low-energy Hamiltonian of these materials.

References in corpus (23)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• $\alpha$-RuCl3: a Spin-Orbit Assisted Mott Insulator on a Honeycomb Lattice
• Models and Materials for Generalized Kitaev Magnetism
• On the Origin of Zigzag Magnetic Order in Iridium Oxide Na2IrO3
• Scattering Continuum and Possible Fractionalized Excitations in $\alpha$-RuCl${}_3$
• Magnetic order in $\alpha$-RuCl${}_3$: a honeycomb lattice quantum magnet with strong spin-orbit coupling
• Quantum spin Hall effect in a transition metal oxide Na2IrO3
• Long range magnetic ordering in Na${}_2$IrO${}_3$
• Kitaev magnetism in honeycomb RuCl3 with intermediate spin-orbit coupling
• Crystal field splitting and correlation effect on the electronic structure of A2IrO3
• Na2IrO3 as a spin-orbit-assisted antiferromagnetic insulator with a 340 meV gap
• Hidden symmetries of the extended Kitaev-Heisenberg model: Implications for honeycomb lattice iridates A2IrO3
• Magnetic anisotropy in the Kitaev model systems Na2IrO3 and RuCl3
• Theory of the field-revealed Kitaev spin liquid
• Unified theory of spiral magnetism in the harmonic-honeycomb iridates α, β, γ Li2IrO3
• Electronic Structure of the Kitaev Material $\alpha$-${\text{RuCl}}_3$ Probed by Photoemission and Inverse Photoemission Spectroscopies
• Electronic and phonon excitations in α-RuCl${}_3$
• High-resolution resonant inelastic x-ray scattering study of the electron-phonon coupling in honeycomb $\alpha$-Li${}_2$IrO${}_3$
• Nearly itinerant electronic groundstate in the intercalated honeycomb iridate Ag${}_3$LiIr${}_2$O${}_6$
• Optical signature of the pressure-induced dimerization in the honeycomb iridate $\alpha$-Li${}_2$IrO${}_3$
• Acoustic phonon dispersion of $\alpha$-RuCl${}_3$
• Optical magnons with dominant bond-directional exchange interactions in a honeycomb lattice iridate $\alpha$-Li${}_2$IrO${}_3$
• Minimal models of $\alpha$-Li${}_2$IrO${}_3$: On the range of the interactions, ground state properties, and magnetization processes

Cited by in corpus (3)

• On the multi-$\mathbf{q}$ characteristics of magnetic ground states of honeycomb cobalt oxides
• Spin-orbit-entangled electronic structure of Ba${}_2$CaOsO${}_6$ studied by O $K$-edge resonant inelastic X-ray scattering
• Evolution of crystal field and intraionic interactions in the ilmenite $A$IrO${}_3$ ($A$ = Mg, Zn, Cd) and hyperhoneycomb $\beta$-ZnIrO${}_3$