  Silicene, a new two-dimensional (2D) material has attracted intense research
because of the ubiquitous use of silicon in modern technology. However,
producing free-standing silicene has proved to be a huge challenge. Until now,
silicene could be synthesized only on metal surfaces where it naturally forms
strong interactions with the metal substrate that modify its electronic
properties. Here, we report the first experimental evidence of silicene sheet
on an insulating NaCl thin film. This work represents a major breakthrough; for
the study of the intrinsic properties of silicene, and by extension to other 2D
materials that have so far only been grown on metal surfaces.
