Floating of critical slates and the QH to insulator transition

The transition from the quantum Hall state to the insulator is considered f or non-interacting electrons in a two-dimensional disordered lattice model with perpendicular magnetic field. Using correlated random disorder potenti als the floating up of the critical states can be observed in a similar way as in the continuum model. Thus, the peculiar behaviour of the lattice mod els reported previously originates in the special choice of uncorrelated ra ndom disorder potentials. (C) 2001 Elsevier Science B.V. All rights reserve d.