| Summary: | 碩士 === 國立成功大學 === 物理學系碩博士班 === 98 === This work investigates the geometric structure and electronic properties of 1D bilayer graphene nanoribbons with AA-stacking and zigzag edge. The Hamiltonian contains the spin-spin interactions, and 4 spin-symmetric structures are simultaneously taken into consideration. We discuss the physical quantities such as the total energy of the system, energy band structures, bonding length as well as interlayer distance, and study the relationship between various spin-symmetric structures and widths. The AFM-AFM has the lowest energy and is the most stable system. The geometric structure shows obvious change only near the edge. The structure with the AFM in the vertical direction exhibits greater curvature and more electron transfer. With respect to the Fermi level, the conduction and valence bands are asymmetric among these four spin structures, and all bands are composed of parabolic ones except the flat bands near the Fermi energy. The interlayer interactions lead to a great deal of band-edge states contributing to the high DOS, which changes obviously along with the increase of the widths. Different spin structures in the vertical direction cause the degeneracy and the splitting of bands near the Fermi energy. The energy spacing at the first Brillouin zone’s boundaries does not vary with the widths. The FM structures result in the characteristics of metals, and the AFM ones belong to the semi-conductors with direct or indirect energy gap of 0.05eV?0.5eV. These gaps will decrease when the widths increase. The predictions could be verified directly by the scanning tunneling microscopy (STM).
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