Anomalous Quantum Diffusion in Order-Disorder Separated Double Quantum Ring

A novel feature for control of carrier mobility is explored in an order-disorder separated double quantum ring, where the two rings thread different magnetic fluxes. Here we use simple tight-binding formulation to describe the system. In our model, the two rings are connected through a single bond and one of the rings is subjected to impurity, keeping the other ring as impurity free. In the strong impurity regime, the electron diffusion length increases with the increase of the impurity strength, while it decreases in the weak impurity regime. This phenomenon is completely opposite to that of a conventional disordered double quantum ring, where the electron diffusion length always decreases with the increase of the disorder strength. PACS No.: 73.23.Ra; 73.23.-b; 73.63.-b