  Defects in graphene, such as vacancies or adsorbents attaching themselves to
carbons, may preferentially take positions on one of its two sublattices, thus
breaking the global lattice symmetry. This leads to opening a gap in the
electronic spectrum. We show that such a sublattice ordering may spontaneously
occur in a dilute ensemble defects, due to the long-range interaction between
them mediated by electrons. As a result sublattice-ordered domains may form,
with electronic properties characteristic of a two-dimensional topological
insulator.
