Well-defined insulating band for electronic transport through a laterally coupled double-quantum-dot chain: Nonequilibrium Green's function calculations

摘要

By means of the nonequilibrium Green function technique, electronic transport through a multiple-quantum-dot system is theoretically studied. In this system, a one-dimensional quantum dot chain between two contacts forms a main channel for the electronic tunneling. Each quantum dot in the chain couples laterally to a dangling quantum dot. Whenever the energy of the incident electron is aligned with the energy levels of the dangling quantum dots, a zero point of the electron transmission function occurs due to the Fano antiresonance. As a result, the linear conductance spectrum presents an insulating band around the antiresonant point. What is interesting is that both edges of the insulating band become steep rapidly with the increase in the numbers of quantum dots. The many-body effect due to the intradot electron interaction on the profile of the insulating band is also investigated by using the equation-of-motion method of the Green functions up to the second-order approximation. It is found that the well-defined insulating band remains. On the basis of this feature, we propose that such a double-quantum-dot chain can be considered as a device prototype of a spin filter.