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

doi:10.1103/PhysRevB.85.195464

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

Department of Physics

Research output: Contribution to journal › Journal article › peer-review

16 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 language	English
Article number	195464
Journal	Physical Review B
Volume	85
Issue number	19
DOIs	https://doi.org/10.1103/PhysRevB.85.195464
Publication status	Published - 30 May 2012

Scopus Subject Areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

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title = "Phase diagram of graphene nanoribbons and band-gap bifurcation of Dirac fermions under quantum confinement",

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.",

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

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AU - Sun, Y. Y.

AU - Ruan, W. Y.

AU - Gao, Xingfa

AU - Bang, Junhyeok

AU - Kim, Yong Hyun

AU - Lee, Kyuho

AU - West, D.

AU - Liu, Xin

AU - CHAN, Anthony T L

AU - Chou, M. Y.

AU - Zhang, S. B.

PY - 2012/5/30

Y1 - 2012/5/30

N2 - 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.

AB - 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.

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U2 - 10.1103/PhysRevB.85.195464

DO - 10.1103/PhysRevB.85.195464

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JO - Physical Review B

JF - Physical Review B

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

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