Size-dependent analysis of the metal-insulator transition in the integral quantum Hall effect

The critical exponent ν of the localization length in the integral quantum Hall regime can be measured directly using the Hall-bar geometries with different sizes. We obtain a universal behavior for the three lowest Landau levels. This is in agreement with the universality prediction of the field-theoretic approach to the metal-insulator transition in the quantum Hall effect. The value of ν=2.3±0.1 agrees with recent numerical studies for the lowest Landau level. The measured value of the temperature exponent of the inelastic-scattering rate is found to range from p=2.7±0.3 to p=3.4±0.4.