| Summary: | 碩士 === 國立高雄大學 === 應用物理學系碩士班 === 101 === The electronic properties of monolayer zigzag graphene nanoribbon in the low energy level show the rich one-dimensional energy band structure. Edge shapes, finite widths, interlayer interactions and magnetic confinement are dominant factors for graphene.
The low-energy band structure of zigzag graphene nanoribbon in the absence of external fields consists of doubly degenerate partial flat bands lying on the Fermi energy (E_F=0) and many parabolic bands symmetric at about E_F=0. Partial flat bands show that the electrons are strongly localized at the zigzag edge. A uniform perpendicular magnetic field constrains electron motion, confining electronic states and inducing dispersionless Landau levels (LLs) in two-dimension graphene systems. In quasi one-dimenesion nanoribbons, boundary conditions imposed by ribbon edges confine the formation of LLs. Hence, there exists a competition between magnetic and quantum confinements. LLs are transformed into quasi-Landau levels (QLLs), and these QLLs gradually disappear as the state energy |E^(c,v) | grows. Furthermore, energy dispersion is symmetric with respect to E_F=0, and partial flat bands are enhanced by a magnetic field.
In this paper, we investigate that the π-electronic properties of bilayer AA stacked zigzag graphene nanoribbon in uniform perpendicular magnetic and electric fields by using the tight-binding model. The main features of the field-modified energy bands are directly reflected in the density of states (DOS), such as the numbers, frequencies, intensities, and divergence forms of prominent peaks.
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