Phase diagram of graphene nanoribbons and band-gap bifurcation of Dirac fermions under quantum confinement

Y. Y. Sun*, W. Y. Ruan, Xingfa Gao, Junhyeok Bang, Yong Hyun Kim, Kyuho Lee, D. West, Xin Liu, Anthony T L CHAN, M. Y. Chou, S. B. Zhang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

A p-T phase diagram of graphene nanoribbons (GNRs) terminated by hydrogen atoms is established based on first-principles calculations, where the stable phase at standard conditions (25 °C and 1 bar) is found to be a zigzag GNR (zzGNR). The stability of this new GNR is understood based on an electron-counting model, which predicts semiconducting nonmagnetic zzGNRs. Quantum confinement of Dirac fermions in the stable zzGNRs is found to be qualitatively different from that in ordinary semiconductors. Bifurcation of the band gap is predicted to take place, leading to the formation of polymorphs with distinct band gaps but equal thermodynamic stability. A tight-binding model analysis reveals the role of edge symmetry on the band-gap bifurcation.

Original languageEnglish
Article number195464
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume85
Issue number19
DOIs
Publication statusPublished - 30 May 2012

Scopus Subject Areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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