Integer quantum Hall transitions in the presence of off-diagonal disorder

We study the disorder-induced quantum Hall-to-insulator transition in a lattice model with only off-diagonal disorder. The localization length of the system is calculated by using the finite-size scaling method combined with the transfer-matrix technique. By increasing the off-diagonal disorder strength we find that the extended states do not float up in energy, but move towards the direction of lower energy. As a consequence, a direct transition from a higher integer quantum Hall state to an insulator becomes possible, in agreement with previous studies based on a tight-binding model with only diagonal disorder