Scaling in plateau-to-plateau transition: A direct connection of quantum hall systems with the Anderson localization model

The quantum Hall-plateau transition was studied at temperatures down to 1mK in a random alloy disordered high mobility two-dimensional electron gas. A perfect power-law scaling with κ=0.42 was observed from 1.2 K down to 12 mK. This perfect scaling terminates sharply at a saturation temperature of Ts∼10mK. The saturation is identified as a finite-size effect when the quantum phase coherence length (L φ T-p/2) reaches the sample size (W) of millimeter scale. From a size dependent study, Ts W-1 was observed and p=2 was obtained. The exponent of the localization length, determined directly from the measured κ and p, is ν=2.38, and the dynamic critical exponent z=1.