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

Abstract

We study the disorder-induced quantum Hall-to-insulator transition in a latticemodel with only off-diagonal disorder. The localization length of the systemis calculated by using the finite-size scaling method combined with thetransfer-matrix technique. By increasing the off-diagonal disorder strength we findthat the extended states do not float up in energy, but move towards the directionof lower energy. As a consequence, a direct transition from a higher integerquantum Hall state to an insulator becomes possible, in agreement with previousstudies based on a tight-binding model with only diagonal disorder.