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arXiv 2103.14263cond-mat.mes-hallphysics.comp-ph
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电场、磁场和$σ$边带对石墨烯纳米带电子光谱和光学光谱的影响

Influence of electric and magnetic fields and $σ$-edge bands on the electronic and optical spectra of graphene nanoribbons

Thi-Nga Do, Po-Hsin Shih, Godfrey Gumbs, Danhong Huang

摘要:

系统研究了扶手椅型和锯齿型石墨烯纳米带在面内横向电场和垂直磁场作用下的电学和光学性质。我们的计算是在广义多轨道紧束缚模型的基础上进行的,该模型考虑了(s,$p_x$,$p_y$,$p_z$)原子轨道之间的跳跃积分以及外部电场和磁场。电子结构由源自$p_z$轨道的$π$带和源自(s,$p_x$,$p_y$)轨道的$σ$带组成。的能带和光谱的多样化的性质的边缘的纳米和强度的外部领域。扶手椅型GNR除了低能的$σ$能带外还显示出宽度依赖的能隙,而Z字形系统具有未填充的平带和在零能量处的$π$边缘态以及部分填充的宽范围$σ$能带。外加面内电场导致能带分裂和费米能级移动,从而丰富了带间和带内的光学电导率。外磁场和边缘几何形状之间的相互作用产生了非常量子化的朗道能级和特殊的光谱。

英文摘要:

The unusual electronic and optical properties of armchair and zigzag graphene nanoribbons (GNRs) subject to in-plane transverse electric and perpendicular magnetic fields have been systematically investigated. Our calculations were carried out within the generalized multi-orbital tight-binding model based on a Hamiltonian which takes into account hopping integrals among the (s, $p_x$, $p_y$, $p_z$) atomic orbitals as well as the external electric and magnetic fields. The electronic structure consists of $π$ bands arising from the $p_z$ orbital and $σ$ bands originating from the (s, $p_x$, $p_y$) orbitals. The energy bands and optical spectra are diversified by both the nature of the edge of the nanoribbon and strength of the external fields. Armchair GNRs display a width-dependent energy gap in addition to low-energy $σ$ bands while the zigzag system has the unfilled flat band with $π$ edge states at zero energy and partially filled wide-range $σ$ bands. An applied in-plane electric field leads to the splitting of energy bands and shifted Fermi level, thereby enriching the inter-band and intra-band optical conductivities. The interplay between an external magnetic field and the edge geometry gives rise to extraordinary quantized Landau levels and special optical spectra.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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