硅烯是由单层硅原子形成的二维蜂窝状晶格结构，具有石墨烯类似的电学性质，由于硅烯中存在比较强的自旋轨道耦合而备受关注。本文利用非平衡格林函数方法研究了门电压控制的硅烯量子线中电子输运性质和能带结构。研究发现，只有在较强的门电压下，而且硅烯量子线具有较好的锯齿形或扶手椅形边界而不存在额外硅原子时，硅烯量子线中才存在无能隙的自旋极化边缘态。另外，计算结果表明这种门电压控制的硅烯量子线中边缘态在每个能谷处自旋是极化的。这些计算结果将为实验上利用电场制作硅烯纳米结构提供理论支持。%Silicene is a two-dimensional honeycomb lattice formed by a monolayer of silicon atoms, which has similar electrical properties to those of graphene. Silicene attracts much attention due to its relatively large spin-orbit coupling. The transport properties through a silicene quantum wire controlled by a gate are studied by using the non-equilibrium Green function formalism. A pair of gapless and spin-polarized edge states appears only when the gate voltage is strong and the silicene quantum wire has perfect zigzag or armchair boundaries in which additional silicon atoms are absent. Moreover, the edge states controlled by gate are spin valley-polarized, that is, the directions of spins are opposite in different valleys, which is different from that of the edge state at the interface between the silicene and vacuum. These results can be helpful to design and fabricate the practical silicene nanostructure.
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