Chiral symmetry breaking and topological charge of zigzag graphene nanoribbons

Hyun Cheol Lee, S. R. Eric Yang

Research output: Contribution to journalArticlepeer-review

Abstract

Interacting quasi-one-dimensional zigzag graphene nanoribbons display gapped edge excitations. Although the self-consistent Hartree-Fock fields break chiral symmetry, our work demonstrates that zigzag graphene nanoribbons maintain their status as short-range entangled symmetry-protected topological insulators. The relevant symmetry involves combined mirror and time-reversal operations. In undoped ribbons displaying edge ferromagnetism, the band gap edge states with a topological charge form on the zigzag edges. An analysis of the anomalous continuity equation elucidates that this topological charge is induced by the gap term. In low-doped zigzag ribbons, where the ground state exhibits edge spin density waves, this topological charge appears as a nearly zero-energy edge mode. Our system is outside the conventional classification for topological insulators.

Original languageEnglish
Article number033039
JournalNew Journal of Physics
Volume26
Issue number3
DOIs
Publication statusPublished - 2024 Mar 1

Bibliographical note

Publisher Copyright:
© 2024 The Author(s). Published by IOP Publishing Ltd on behalf of the Institute of Physics and Deutsche Physikalische Gesellschaft

Keywords

  • symmetry protected topological insulator
  • topological charge
  • zigzag nanoribbon

ASJC Scopus subject areas

  • General Physics and Astronomy

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