Long-range orientational order in a two-dimensional degenerate system of dipoles on a square lattice

It is shown that in a planar degenerate system on a square lattice with dipole-dipole interactions of electric or magnetic moments the thermodynamic fluctuations destroy the Goldstone mode in the spectrum of orientational oscillations. This gives rise to layered antiferroelectric structures characterized by a nonzero long-range orientational order parameter, which in the low-temperature limit is proportional to exp(-T/lnT/). (C) 1996 American Institute of Physics.