Spontaneous Breakdown of Translational Symmetry in Quantum Hall Systems:   Crystalline Order in High Landau Levels
  We report on results of systematic numerical studies of two-dimensional electron gas systems subject to a perpendicular magnetic field, with a high Landau level partially filled by electrons. Our results are strongly suggestive of a breakdown of translational symmetry and the presence of crystalline order in the ground state. This is in sharp contrast with the physics of the lowest and first excited Landau levels, and in good qualitative agreement with earlier Hartree-Fock studies. Experimental implications of our results are discussed. 
F.D.M. Haldane, E H. Rezayi, and Kun Yang