Geometric and electronic structure of graphene bilayer edges

Phys. Rev. B 80, 165407 (2009), Ji Feng, Liang Qi, Jian Yu Huang, and Ju Li

We present a computational investigation of free-standing graphene bilayer edge (BLE) structures, aka
“fractional nanotubes.” We demonstrate that these curved carbon nanostructures possess a number of interesting
properties, electronic in origin. The BLEs, quite atypical of elemental carbon, have large permanent electric
dipoles of 0.87 and 1.14 debye/Å for zigzag and armchair inclinations, respectively. An unusual, weak AA
interlayer coupling leads to a twinned double-cone dispersion of the electronic states near the Dirac points.
This entails a type of quantum Hall behavior markedly different from what has been observed in graphenebased
materials, characterized by a magnetic field-dependent resonance in the Hall conductivity.