Phase diagram of the integer quantum Hall effect

The phase diagram of the integer quantum Hall effect is numerically determi ned in the tight-binding model, which can account for overall features of r ecently obtained experimental phase diagram with direct transitions from hi gh plateau states to the insulator. In particular, the quantum Hall plateau s are terminated by two distinct insulating regimes, characterized by the H all resistance with classic and quantized values, respectively, which is al so in good agreement with experiments. The physical origin of this peculiar phase diagram is discussed.