Computational design of graphene nanoribbons with tunable topological properties*

During the last decade, on-surface synthesis techniques have paved the way to obtain atomically-precise bottom-up graphene nanoribbons (GNRs). In this context, the unprecedented level of control of the chemical substitution and overall morphology of the GNRs has given rise to the exploration of novel features in these systems, such as topological phases and magnetic properties.

In this work, Density Functional Theory simulations are performed to achieve atomic-level insights into the electronic structure and topological properties of a set of width-modulated pristine GNRs. The consequences of altering the ribbon morphology are studied by considering ribbons with sections of unequal widths that have different lengths. We found that GNRs from the same structural family can exhibit different Zak phases and that the proper combination of diverse segments allows tuning the band gap and topology of the composite system. Our results might prove relevant for the design of new experiments to further describe these materials, as well as for the development of novel devices in a vast assortment of applications in nanoelectronics.