Quasiparticles and charge transfer at the two surfaces of the honeycomb iridate Na${}_2$IrO${}_3$

Abstract

Direct experimental investigations of the low-energy electronic structure of the Na${}_2$IrO${}_3$ iridate insulator are sparse and draw two conflicting pictures. One relies on flat bands and a clear gap, the other involves dispersive states approaching the Fermi level, pointing to surface metallicity. Here, by a combination of angle-resolved photoemission, photoemission electron microscopy, and x-ray absorption, we show that the correct picture is more complex and involves an anomalous band, arising from charge transfer from Na atoms to Ir-derived states. Bulk quasiparticles do exist, but in one of the two possible surface terminations the charge transfer is smaller and they remain elusive.

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Cited by in corpus (9)

• Interacting topological insulators: a review
• Competition between magnetic order and charge localization in Na${}_2$IrO${}_3$ thin crystal devices
• Topological property of a $t_{2g}^5$ system with a honeycomb lattice structure
• Dynamics of a single hole in the Heisenberg-Kitaev model: a self-consistent Born approximation study
• Conductivity of Dirac-like surface states in correlated honeycomb transition metal oxide Mott insulators
• Spectrum of the hole excitation in spin-orbit Mott insulator Na${}_2$IrO${}_3$
• Electronic transport mechanisms in a thin crystal of the Kitaev candidate $\alpha$-RuCl${}_3$ probed through guarded high impedance measurements
• Enhanced Magnetism and Phase Transitions in Ultrathin Quantum Spin Liquid Na2IrO3 Flakes
• Metallic conductivity on Na-deficient structural domain walls in the spin-orbit Mott insulator Na${}_2$IrO${}_3$