DELOCALIZATION OF ELECTRONS IN A RANDOM MAGNETIC-FIELD

Delocalization problem for a two-dimensional noninteracting electron s ystem under a random magnetic field is studied. The Chern number is us ed to characterize the extended states in such a system, and by studyi ng finite-size scaling of the density of extended states, an insulator -metal phase transition is revealed. The delocalization phase is found at the center of the energy band separated from the localized band ta ils by critical energies +/-E(c). Both the localization exponent and t he critical energy E(c) are shown to be dependent on the strength of t he random magnetic field.