Lattice on Lattice in Two Dimensions

We study a harmonic triangular lattice, which relaxes in the presence of a weak, short-wavelength periodic potential. Monte Carlo simulations reveal that the elastic lattice has only short-ranged positional correlations, despite the absence of defects in either lattice. Long-range orientational order, however, persists in the presence of the background. Our results provide an alternative explanation for the hexatic glassphase observed in high-temperature superconductors, magnetic bubble lattices, and charge density waves in semiconductors.