New insights into the plateau–insulator transition in the quantum Hall regime

We have measured the quantum critical behavior of the plateau–insulator (PI) transition in a low-mobility InGaAs/GaAs quantum well. The longitudinal resistivity measured for two different values of the electron density follows an exponential law, from which we extract critical exponents κ=0.54 and 0.58, in good agreement with the value (κ=0.57) previously obtained for an InGaAs/InP heterostructure. This provides evidence for a non-Fermi liquid critical exponent. By reversing the direction of the magnetic field we find that the averaged Hall resistance remains quantized at the plateau value h/e2 through the PI transition. From the deviations of the Hall resistance from the quantized value, we obtain the corrections to scaling.