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arXiv 1601.02785cond-mat.mes-hallcond-mat.mtrl-sci
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Bi2Se3拓扑绝缘体纳米线的带隙:磁性和几何效应

Band gap in Bi2Se3 topological insulator nanowires: magnetic and geometrical effects

P. Iorio, C. A. Perroni, V. Cataudella

摘要:

在三维拓扑绝缘体纳米线干涉仪实现的激励下,从理论上分析了量子干涉效应对Bi_2Se_3纳米线低能谱的影响.从连续三维模型开始,特别强调磁性和几何效应的电子性质的圆形,方形和矩形截面的纳米线进行了分析。理论研究是基于数值精确对角化的离散模型的所有几何形状。在圆柱形导线的情况下,连续介质模型的近似解析解也进行了讨论。虽然预期对应于半量子通量的磁场将闭合由Berry相引起的带隙,但是在具有有限面积横截面的所有研究的几何结构中,间隙对于通常大于预期的磁场闭合。此外,出乎意料地,由于几何量子干涉效应,对于具有足够大的纵横比和范围从50°A到100°A的较小边的矩形导线,间隙对于特定的有限面积横截面闭合,而不施加磁场。

英文摘要:

Stimulated by the recent realization of three dimensional topological insulator nanowire interfer- ometers, a theoretical analysis of quantum interference effects on the low energy spectrum of Bi2Se3 nanowires is presented. The electronic properties are analyzed in nanowires with circular, square and rectangular cross-sections starting from a continuum three dimensional model with particular emphasis on magnetic and geometrical effects. The theoretical study is based on numerically exact diagonalizations of the discretized model for all the geometries. In the case of the cylindrical wire, an approximate analytical solution of the continuum model is also discussed. Although a magnetic field corresponding to half quantum flux is expected to close the band gap induced by Berry phase, in all the studied geometries with finite area cross-sections, the gap closes for magnetic fields typically larger than those expected. Furthermore, unexpectedly, due to geometrical quantum interference effects, for a rectangular wire with a sufficiently large aspect ratio and smaller side ranging from 50°A and 100°A, the gap closes for a specific finite area cross-section without the application of a magnetic field.

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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