Orderings of a stacked frustrated triangular system in three dimensions

An Ising system is constructed by stacking frustrated antiferromagnetic triangular lattices. Landau-Ginzburg-Wilson and Monte Carlo analyses suggest two ordered phases. In the low-temperature phase, one sublattice is fully ordered and, oppositely, two sublattices are partially ordered. In the intermediate phase, two sublattices are fully and oppositely ordered, and one is disordered. The transition to the paramagnetic phase is in XY universality. The transition between the ordered phases is due to sixfold symmetry-breaking flop.