Disorder-tuned transition between a quantum Hall liquid and Hall insulator

We report measurements of the disorder-driven phase transition from a quantum Hall liquid to Hall insulator at ν=1/3 and ν=2 observed in a two-dimensional electron gas. The data show good scaling behavior over a wide range of densities and temperatures with an exponent 1/zx∼0.43 for both ν=1/3 and 2, where z is the dynamical exponent and x is the correlation length exponent. The critical conductance at the transition is found to be σxx=0.09±0.01e2/h for the ν=1/3 transition and σxx=0.9±0.15e2/h for the ν=2 case