抄録
Applying the self-consistent diagramatic treatment of the dynamical diffusion coefficient of the two dimensional electron system under quantizing magnetic fields to the case where only one type of short-range impurities are present, the meaning of the “subband center” is reconsidered. The localization length calculated as a function of the filling factor of the lowest Landau subband is shown to become infinite at one point whose position is determined by the impurity concentration. This result indicates that the measurement of the Hall step position yields an information about the impurity concentration.