Supersolid Order from Disorder: Hard-Core Bosons on the Triangular   Lattice
  We study the interplay of Mott localization, geometric frustration, and superfluidity for hard-core bosons with nearest-neighbor repulsion on the triangular lattice. For this model at half-filling, we demonstrate that superfluidity survives for arbitrarily large repulsion, and that diagonal solid order emerges in the strongly correlated regime from an order-by-disorder mechanism. This is thus an unusual example of a stable supersolid phase of hard-core lattice bosons at a commensurate filling. 
R. G. Melko, A. Paramekanti, A. A. Burkov, A. Vishwanath, D. N. Sheng   and L. Balents