Spin-Resolved Electronic and Transport Properties of Graphyne-Based Nanojunctions with Different N-Substituting Positions.

Since the rapid development of theoretical progress on the two-dimensional graphyne nanoribbons and nanojunctions, here we investigate the electronic band structures and transport properties for the junctions based on armchair-edged γ-graphyne nanoribbons (AγGYNRs) with asymmetrically nitrogen (N)-substituting in the central carbon hexagon. By employing first-principles calculation, our computational results imply that the number and the location of single or double N-doping can efficiently modulate the electronic energy band, and the N-doping hexagonal rings in the middle of the junction play a vital role in the charge transport. In specific, the effect of negative difference resistance (NDR) is observed, in which possesses the biggest peak to valley ratio reaching up to 36.8. Interestingly, the N-doped junction with longer molecular chain in the central scattering region can induce a more obvious NDR behavior. The explanation of the mechanism in the microscopic level has suggested that the asymmetrically N-doped junction by introducing a longer molecular chain can produce a more notable pulse-like current-voltage dependence due to the presence of a transporting channel within the bias window under a higher bias voltage. In addition, when the spin injection is considered, an intriguing rectifying effect in combination with NDR is available, which is expected to be applied in future spintronic devices.