Size Effects on Topological Anderson Insulator

We study the size effects on the transport properties in topological Anderson insulator by means of the Landauer-B\"uttiker formalism combined with the nonequilibrium Green function method. Conductances calculated for serval different width of the nanoribbons reveal that there is no longer quantized plateaus for narrow nanoribbons. The local spin polarized current distribution demonstrates that the edge states on the two sides can be coupled, leading to enhancement of backscattering as the width of the nanoribbon decreases, thus destroying the perfect quantization phenomena in the topological Anderson insulator. It is also demonstrated that the main contribution to the nonquantized conductance (with a hump structure) also comes from edge states.