  We study a superlattice of silicene and hexagonal boron nitride by first
principles calculations and demonstrate that the interaction between the layers
of the superlattice is very small. As a consequence, quasi free-standing
silicene is realized in this superlattice. In particular, the Dirac cone of
silicene is preserved, which has not been possible in any other system so far.
Due to the wide band gap of hexagonal boron nitride, the superlattice realizes
the characteristic physical phenomena of free-standing silicene. In particular,
we address by model calculations the combined effect of the intrinsic
spin-orbit coupling and an external electric field, which induces a transition
from a metal to a topological insulator and further to a band insulator.
