Observation of a Flat Band in Silicene

The electronic structure of silicene on Ag(111) is studied by scanning tunneling microscopy and angle resolved photoemission spectroscopy. A flat band at 0.9 eV below the Fermi level is revealed. We find that the flat band is strongly suppressed near atomic defects, domain boundaries and step edges compared to that on the flat terraces. The discovery of the flat band and its sensitivity to local perturbations provides a new way to manipulate the electronic structure and properties of silicene.