2021/09/15 by Michele Pizzochero, Nikita V. Tepliakov, Arash A. Mostofi +1
Physics and Astronomy · #cond-mat.mtrl-sci #cond-mat.mes-hall
paper · pdf · doi:10.1021/acs.nanolett.1c03596
published as Nano Lett. 21, 9332 (2021)
arxiv created 2021/09/15 · arxiv updated 2021/11/11
Graphene nanoribbons are widely regarded as promising building blocks for next-generation carbon-based devices. A critical issue to their prospective applications is whether and to what degree their electronic structure can be externally controlled. Here, we combine simple model Hamiltonians with extensive first-principles calculations to investigate the response of armchair graphene nanoribbons to transverse electric fields. Such fields can be achieved either upon laterally gating the nanoribbon or incorporating ambipolar chemical co-dopants along the edges. We reveal that the field induces a semiconductor-to-semimetal transition, with the semimetallic phase featuring zero-energy Dirac fermions that propagate along the armchair edges. The transition occurs at critical fields that scale inversely with the width of the nanoribbons. These findings are universal to group-IV honeycomb lattices, including silicene and germanene nanoribbons, irrespective of the type of edge termination. Overall, our results create new opportunities to electrically engineer Dirac fermions in otherwise semiconducting graphene-like nanoribbons.