Absence of Dirac cones in monolayer silicene and multilayer Si films on Ag(111)

Monolayer silicene and multilayer silicon films on Ag(111) have been the subject of many investigations within the last few years. For both systems, photoemission data have been interpreted in terms of linearly dispersing bands giving rise to the characteristic Dirac cone features, similar to graphene. Here we demonstrate, on the basis of angle-resolved valence band and core level photoemission data that this assignment is not correct. The bands previously attributed to states with Dirac fermion character are shown to derive from Ag(111) interface and bulk states in the silicene monolayer and from the well-known Ag-(3×3)R30°-Si(111) structure in Si multilayers. These results question the validity of the claim that graphene-like silicene and silicene multilayers are in fact formed on Ag(111).