| Summary: | 博士 === 國立成功大學 === 物理學系碩博士班 === 97 === The electronic properties of monolayer and bilayer nanocarbon systems
(single- and double-walled finite carbon nanotubes, ribbon-graphene hybrid systems, and carbon nanotube-nanoribbon hybrids) are studied within the tight-binding model, and first-principles calculations.
The low-energy states of single-walled finite carbon nanotubes are predominated by the geometrical structure and tube length.
The peculiar localized states of the zigzag nanotube could be modulated by the magnetic and electric fields.
The intertube atomic hoppings in double-walled finite carbon nanotubes significantly influence the variations of the low energy states under the external fields.
In addition, the different boundary structures induced by the inner and outer tube also play an important role in the electronic properties.
As for the ribbon-graphene hybrid systems, the graphene nanoribbons are aligned on the single-layer graphene in a periodical manner.
The band structures are investigated with different widths and periods of the ribbon, as well as the stacking type.
The linear bands crossing at the Fermi level originated from the graphene change into the parabolic bands and open an energy gap owing to the interlayer interactions.
These systems reveal the quasi-one-dimensional peaks in the density of states.
After considering the spin orientation, the hybrids consisting of the armchair nanotube lying on the zigzag ribbon are more stable in the antiferromagnetic configurations.
The nanotube location on the ribbon would be associated with the stacking arrangement and studied in detail.
The interlayer interactions would also break the intersection of the linear band from the armchair carbon nanotube.
The shifting of tube toward the ribbon edge would destroy the degeneracy of spin-up and spin-down states in the antiferromagnetic configuration.
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