Topological phases in nitrogen-doped chevron graphene nanoribbons

Researches on one-dimensional topological insulators have garnered significant attention following the discovery of symmetry-protected topological phases in graphene nanoribbons (GNRs). The topological properties of GNRs are modulated by shape modulation, such as altering the width, edge structure, and unit cell termination. Compared to shape modulation, the introduction of foreign atoms doping in the unit cell has proven more practical. However, the impact of doping on topological properties and the underlying mechanisms remain incompletely understood. In this study, nitrogen doping in chevron GNR is utilized to investigate the mechanism of the topological properties with different doping concentrations. The nitrogen doping reduces the intracell hopping parameter, and transforms the GNR from trivial to nontrivial when the doping level reaches eight nitrogen atoms per unit cell. Additionally, the GNR junctions comprising the chevron-GNR and pristine armchair GNRs demonstrate antiferromagnetic exchange coupling. These findings may inform future experimental design of GNR-based electronic devices.