标题： 选择性磁掺杂拓扑绝缘体纳米线中的输运特性 显示英文标题

标题： Transport in Selectively Magnetically Doped Topological Insulator Wires

摘要： 我们研究了拓扑绝缘体纳米线的电子和输运特性，包括其表面的选择性磁掺杂。 我们使用一个模型，该模型适用于描述像Bi$_2$Se$_3$这样的材料，在k.p近似下进行描述，并考虑矩形几何结构的纳米线。 在这个模型中，(111)表面上的磁掺杂会诱导出一个Zeeman场，这会在对应于表面态的狄拉克锥处打开一个能隙。 为了获得两终端配置下的输运特性，我们使用一种基于紧束缚模型的递归格林函数方法，该模型是通过对原始连续模型进行离散化得到的。 对于两个相对纳米线(111)表面的均匀磁化情况，我们展示了当磁化方向相同时，电导可以处于一个量子化的值$e^2/h$，而当磁化方向相反时，电导则变得非常小。 我们还分析了非均匀磁化的情况，在这种情况下，两个相对表面上的Zeeman场在纳米线中间处改变符号。 在这种情况下，我们发现可以通过纳米线中间处束缚的螺旋态进行共振隧穿来实现导电。 通过在纳米线横截面上施加Aharonov-Bohm通量，可以调节共振能级的位置。 显示英文摘要

摘要： We study the electronic and transport properties of a topological insulator nanowire including selective magnetic doping of its surfaces. We use a model which is appropriate to describe materials like Bi$_2$Se$_3$ within a k.p approximation and consider nanowires with a rectangular geometry. Within this model the magnetic doping at the (111) surfaces induces a Zeeman field which opens a gap at the Dirac cones corresponding to the surface states. For obtaining the transport properties in a two terminal configuration we use a recursive Green function method based on a tight-binding model which is obtained by discretizing the original continuous model. For the case of uniform magnetization of two opposite nanowire (111) surfaces we show that the conductance can switch from a quantized value of $e^2/h$ (when the magnetizations are equal) to a very small value (when they are opposite). We also analyze the case of non-uniform magnetizations in which the Zeeman field on the two opposite surfaces change sign at the middle of the wire. For this case we find that conduction by resonant tunneling through a chiral state bound at the middle of the wire is possible. The resonant level position can be tuned by imposing an Aharonov-Bohm flux through the nanowire cross section.