Edge states of zigzag bilayer graphite nanoribbons
Abstract
The electronic structures of zigzag bilayer graphite nanoribbons (Z-BGNRs) with various ribbon widths N are studied within the tight binding approximation. Neglecting the inter-layer hopping amplitude γ4, which is an order of magnitude smaller than the other inter-layer hopping parameters, there exist two fixed Fermi points ± k* independent of the ribbon width with a peculiar energy dispersion near k* as ɛ(k)~ ± (k-k*)N. By investigating the edge states of Z-BGNRs, we notice that the trigonal warping of the bilayer graphene sheets is reflected in the edge state structure. With the inclusion of γ4, the above two Fermi points are not fixed but drift toward the vicinity of the Dirac point with increasing width N, as shown by the finite scaling method, and the peculiar dispersions change to parabolic ones. The edge magnetism of Z-BGNRs is also examined by solving the half-filled Hubbard Hamiltonian for the ribbon using the Hartree-Fock approximation. We have shown that within the same side of the edges, the edge spins are aligned ferromagnetically for the experimentally relevant set of parameters.
- Publication:
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Journal of Physics Condensed Matter
- Pub Date:
- September 2008
- DOI:
- 10.1088/0953-8984/20/36/365202
- arXiv:
- arXiv:0806.1077
- Bibcode:
- 2008JPCM...20J5202R
- Keywords:
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- Condensed Matter - Mesoscale and Nanoscale Physics
- E-Print:
- 22 pages, 7 figures