Numerical study of delocalized states in an extended network model

We have extended the Chalker-Coddington network model to a coupled double layer system with reversed magnetic field directions. The model is investigated numerically and focused on the behavior of the delocalized states. When the hybridization between the layers is small, there axe two separate energies of the delocalized states with opposite sign. At some randomness strength, we have observed large fluctuation of the extended state energies. Furthermore, with sufficient strong hybridization, we do not find the delocalized states which suggests the disappearance of the delocalized states at finite hybridization strength. The critical property is also investigated in the weak randomness case which is consistent with the standard single layer case.