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arXiv · 1710.11602

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

L. Moreschini·I. Lo Vecchio·N. P. Breznay·S. Moser·S. Ulstrup·R. Koch·J. Wirjo·C. Jozwiak·K. S. Kim·E. Rotenberg·A. Bostwick·J. G. Analytis·A. Lanzara
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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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L. Moreschini, I. Lo Vecchio, N. P. Breznay, S. Moser, S. Ulstrup, R. Koch, J. Wirjo, C. Jozwiak, K. S. Kim, E. Rotenberg, A. Bostwick, J. G. Analytis, A. Lanzara. 2017-10-31. Quasiparticles and charge transfer at the two surfaces of the honeycomb iridate Na$_2$IrO$_3$. https://doi.org/10.1103/physrevb.96.161116

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