Integer quantum Hall effect in a triangular-lattice: Disorder effect and scaling behavior of the insulator-plateau transition

We investigate numerically the integer quantum Hall effect in a three-band triangular-lattice model. The three bands own the Chern number C=2,−1,−1, respectively. The lowest topological flat band carrying Chern number C=2, which leads to the Hall plateau σH=2(e2/h). This Hall plateau is sensitive to the disorder scattering and is rapidly destroyed by the weak disorder. Further increasing the strength of disorder, the gap of density of states always disappears before the vanishing of the corresponding Hall plateau. The scaling behavior of quantum phase transition between an insulator and a quantum Hall plateau is studied. We find that the insulator-plateau transition becomes sharper with increasing the size of system. Due to the different of edge states, the critical energy Ec1 gradually shifts to the center of Hall plateau while Ec2 is unaffected with increasing the disorder strength.