Title: 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.