Corrections to Scaling in the Integer Quantum Hall Effect

Finite size corrections to scaling laws in the centers of Landau levels are studied systematically by numerical calculations. The corrections can account for the apparent non-universality of the localization length exponent $\nu{}$. In the second lowest Landau level the irrelevant scaling index is $y_{\mathrm{irr}}=-0.38\pm0.04$. At the center of the lowest Landau level an additional periodic potential is found to be irrelevant with the same scaling index. These results suggest that the localization length exponent $\nu$ is universal with respect to Landau level index and an additional periodic potential.