Fractional Hofstadter States in Graphene on Hexagonal Boron Nitride
  In fractionally filled Landau levels there is only a small energy difference between broken translational symmetry electron-crystal states and exotic correlated quantum fluid states. We show that the spatially periodic substrate interaction associated with the long period moir\'{e} patterns present in graphene on nearly aligned hexagonal boron nitride (hBN) tilts this close competition in favor of the former, explaining surprising recent experimental findings. 
Ashley M. DaSilva, Jeil Jung, Allan H. MacDonald
cond-mat.mes-hall