Half-metallic quantum valley Hall effect in biased zigzag-edge bilayer graphene nanoribbons
- Authors
- Lee, Kyu Won; Lee, Cheol Eui
- Issue Date
- 27-2월-2017
- Publisher
- AMER PHYSICAL SOC
- Citation
- PHYSICAL REVIEW B, v.95, no.8
- Indexed
- SCIE
SCOPUS
- Journal Title
- PHYSICAL REVIEW B
- Volume
- 95
- Number
- 8
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/84396
- DOI
- 10.1103/PhysRevB.95.085145
- ISSN
- 2469-9950
- 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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