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

The critical exponent 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 =2. 30. 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. 70. 3 to p=3. 40. 4.