Electronic Structure of the Kitaev Material $\alpha$-${\text{RuCl}}_3$ Probed by Photoemission and Inverse Photoemission Spectroscopies

Abstract

Recently, $\alpha$-${\text{RuCl}}_3$ has attracted much attention as a possible material realization of the honeycomb Kitaev model, which may stabilize a quantum-spin-liquid state. Compared to extensive studies on its magnetic properties, there is still a lack of understanding on its electronic structure, which is strongly related with its Kitaev physics. Here, the electronic structure of $\alpha$-${\text{RuCl}}_3$ is investigated by photoemission (PE) and inverse photoemission (IPE) spectroscopies. The band gap, directly measured from PE/IPE spectra, is found to be 1.9 eV, much larger than previous estimations. The LDA calculations show that the on-site Coulomb interaction $\text{U}$ can open the band gap without spin-orbit coupling (SOC). However, the SOC should also be incorporated to reproduce the proper gap size, indicating that the interplay between $\text{U}$ and SOC plays an essential role in the physics of $\alpha$-${\text{RuCl}}_3$. There exist some spectral features in PE/IPE spectra which cannot be explained by the LDA calculations. To explain such discrepancies, we perform the configuration-interaction calculations for a ${\text{RuCl}}_6^{3-}$ cluster. The experimental data and calculations demonstrate that the 4$\text{d}$ compound $\alpha$-${\text{RuCl}}_3$ is a $J_{\text{eff}}$ = 1/2 Mott insulator rather than a quasimolecular-orbital insulator. Our study also provides important physical parameters, required in verifying the proposed Kitaev physics in $\alpha$-${\text{RuCl}}_3$.

22 pages, 4 figures

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Cited by in corpus (32)

• Models and Materials for Generalized Kitaev Magnetism
• Electronic and phonon excitations in α-RuCl${}_3$
• Floquet engineering of Kitaev quantum magnets
• Inverse Faraday effect in Mott insulators
• Ground-state phase diagram of spin-$S$ Kitaev-Heisenberg models
• Light-Induced Control of Magnetic Phases in Kitaev Quantum Magnets
• Direct visualization of the charge transfer in Graphene/$\alpha$-RuCl${}_3$ heterostructure
• Anisotropy as a diagnostic test for distinct tensor network wavefunctions of integer and half-integer spin Kitaev quantum spin liquids
• Emergent orbital magnetization in Kitaev quantum magnets
• Tunneling spectroscopic signatures of charge doping and associated Mott transition in $\alpha$-RuCl${}_3$ in proximity to graphite
• Oscillations of the thermal conductivity observed in the spin-liquid state of $\alpha$-RuCl${}_3$
• Feasibility of Kitaev quantum spin liquids in ultracold polar molecules
• Contrasting electronic states of RuI3 and RuCl3
• Magnetic anisotropy energies and metal-insulator transitions in monolayers of $\alpha$-RuCl${}_3$ and OsCl${}_3$ on graphene
• Single-hole spectra of Kitaev spin liquids: from dynamical Nagaoka ferromagnetism to spin-hole fractionalization
• Toward improved property prediction of 2D materials using many-body quantum Monte Carlo methods
• Electronic structure of $\mathbf{\alpha }$-RuCl${}_3$ by fixed-node and fixed-phase diffusion Monte Carlo methods
• Ground-State Phase Diagram of the Kitaev-Heisenberg Model on a Three-dimensional Hyperhoneycomb Lattice
• Insulator-to-metal Mott transition facilitated by lattice deformation in monolayer $\alpha$-RuCl${}_3$ on graphite
• Nonequilibrium dynamics of $\alpha$-RuCl${}_3$ -- a time-resolved magneto-optical spectroscopy study
• Non-local features of the spin-orbit exciton in Kitaev materials
• From linear to circular polarized light -- Floquet engineering in Kitaev-Heisenberg materials with Lissajous figures
• Mott Gap Softening Coinciding with Spin Correlations Collapse in a-RuCl3
• Possible Realization of Kitaev Spin Liquids in van der Waals Heterostructures of $\alpha$-RuCl${}_3$ and Cr$X_3$ ($X$=Cl and I)
• Electronic transport mechanisms in a thin crystal of the Kitaev candidate $\alpha$-RuCl${}_3$ probed through guarded high impedance measurements
• Topological Majorana flat bands in the Kitaev model on a Bishamon-kikko lattice
• Schwinger boson theory for $S=1$ Kitaev quantum spin liquids
• Spin-phonon coupling and thermal Hall effect in the Kitaev model
• Order-by-disorder from Schwinger bosons in a frustrated honeycomb ferromagnet
• Strain-induced Landau levels of Majorana fermions in an anisotropically interacting Kitaev model on a honeycomb lattice
• Magnetic field effects on the Kitaev model coupled to environment
• Vortex creation and control in the Kitaev spin liquid by local bond modulations