Spin-filter and Fano antiresonant effect in conductance through a zigzaglike polymer device: nonequilibrium Green's...

Electronic transport through a quasi-one-dimensional zigzaglike polymer device is theoretically studied by means of the nonequilibrium Green's function approach. In this system, the main zigzag chain consists of carbon atoms and is attached with side radicals at its next-near-neighbor sites. The results show that a zero point of the linear conductance spectrum occurs due to the Fano antiresonance induced by the electron hoppings between the main chain and the side radicals, which leads to the fact that the linear conductance spectrum displays an insulating band around the antiresonant point. The increase in the polymer size makes both edges of the insulating band to become steep rapidly, which makes the insulating band approach to be a well-defined one. The formation of the dimer along the main chain enhances the insulating band width but much suppresses the electronic transport through the device. Moreover, if the many-body effect due to the electron interaction is taken into account, the antiresonance effect and the well-defined insulating band remain. As a result, a well spin-polarized window appears as the spin splitting occurred by applying an external magnetic field. These results strongly propose that there is a new way for the organic polymer to be applied as a spin-filter.