Multilayered silicene: the bottom-up approach for a weakly relaxed Si(111) with Dirac surface states

Combining first principles investigations and scanning tunneling microscopy, we identify that the presumable van der Waals packed multilayered silicene sheets spontaneously transform into a diamond-structure bulk Si film due to strong interlayer couplings. In contrast to drastic surface reconstruction on conventional Si(111), multilayered silicene prepared by bottom-up epitaxy on Ag(111) exhibits a nearly ideal flat surface with only weak buckling. Without invoking Ag surfactants, root 3 x root 3 honeycomb patterns emerge thanks to dynamic fluctuation of mirror-symmetric rhombic phases, similar to monolayered silicene [Chen et al., Phys. Rev. Lett., 2013, 110, 085504]. The weak relaxation enables novel surface states with a Dirac linear dispersion.