Half-metallic quantum valley Hall effect in biased zigzag-edge bilayer graphene nanoribbons

Kyu Won Lee, Cheol Eui Lee

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We have investigated electron-electron interaction effects on gapless edge states in the antiferromagnetic phase of zigzag-edge bilayer graphene nanoribbons under a voltage bias between the layers by using a tight-binding model with on-site Coulomb interactions. We found that a zigzag-edge bilayer graphene nanoribbon can have gapless edge states corresponding to peculiar topologically nontrivial insulator phases, such as a half-metallic quantum valley Hall phase. The half-metallicity was found to be due to the on-site Coulomb interactions through which excess charges produced by the voltage bias between the layers give rise to the potential difference between the opposite edges. A topological phase diagram in the antiferromagnetic phase of a zigzag-edge bilayer graphene nanoribbon was determined as a function of the bias voltage and the ribbon width. The quantum confinement effect, which was found to be graphene-like for narrow ribbons and to be bilayer graphene-like for wide ribbons, was also confirmed to play an important role in determining the topologically nontrivial insulator phases.

Original languageEnglish
Article number085145
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume95
Issue number8
DOIs
Publication statusPublished - 2017 Feb 27

Fingerprint

Quantum Hall effect
Nanoribbons
Carbon Nanotubes
Graphite
Graphene
valleys
Hall effect
graphene
Bias voltage
ribbons
Coulomb interactions
electric potential
Electron-electron interactions
insulators
Quantum confinement
Phase diagrams
metallicity
electron scattering
phase diagrams
interactions

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

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abstract = "We have investigated electron-electron interaction effects on gapless edge states in the antiferromagnetic phase of zigzag-edge bilayer graphene nanoribbons under a voltage bias between the layers by using a tight-binding model with on-site Coulomb interactions. We found that a zigzag-edge bilayer graphene nanoribbon can have gapless edge states corresponding to peculiar topologically nontrivial insulator phases, such as a half-metallic quantum valley Hall phase. The half-metallicity was found to be due to the on-site Coulomb interactions through which excess charges produced by the voltage bias between the layers give rise to the potential difference between the opposite edges. A topological phase diagram in the antiferromagnetic phase of a zigzag-edge bilayer graphene nanoribbon was determined as a function of the bias voltage and the ribbon width. The quantum confinement effect, which was found to be graphene-like for narrow ribbons and to be bilayer graphene-like for wide ribbons, was also confirmed to play an important role in determining the topologically nontrivial insulator phases.",
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