THE 2-DIMENSIONAL ANDERSON MODEL OF LOCALIZATION WITH RANDOM HOPPING

We examine the localization properties of the 2D Anderson Hamiltonian with off-diagonal disorder. investigating the behavior of the particip ation numbers of eigenstates as well as studying their multifractal pr operties, we find states in the center of the band which show critical behavior up to the system size N = 200 x 200 considered. This result is confirmed by an independent analysis of the localization lengths in quasi-1D strips with the help of the transfer-matrix method. Adding a very small additional onsite potential disorder, the critical states become localized.