Finite-size energy gap in weak and strong topological insulators
Finite-size energy gap in weak and strong topological insulators
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DOI：
10.1103/physrevb.86.245436
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发表时间：
2012-12-28
影响因子：
3.7
通讯作者：
Ohtsuki, Tomi
中科院分区：
文献类型：
--
作者：
Imura, Ken-Ichiro;Okamoto, Mayuko;Ohtsuki, Tomi
拓扑绝缘体（TI）的非平凡性的特征在于要么通过体拓扑不变量或通过存在的保护金属表面状态。然而，在有限大小的实际样品中，这种非平凡性并不一定保证表面态的无隙性。根据几何结构和拓扑指数，可以出现不同性质的有限尺寸的能隙，并且相应地，表现出差距的各种标度行为。自旋-表面锁定提供了一种这样的间隙开放机制，导致能隙的幂律缩放。弱TI和强TI对样品的几何形状表现出不同程度的敏感性。作为一个值得注意的例子，一个强TI纳米线的矩形棱柱形状被证明是更多的间隙比弱TI的完全相同的几何形状。DOI：10.1103/PhysRevB.86.245436 PACS编号：73.22.- f，73.20.At，72.80.Sk
The nontrivialness of a topological insulator (TI) is characterized either by a bulk topological invariant or by the existence of a protected metallic surface state. Yet, in realistic samples of finite size, this nontrivialness does not necessarily guarantee the gaplessness of the surface state. Depending on the geometry and on the topological indices, a finite-size energy gap of different nature can appear, and, correspondingly, exhibit various scaling behaviors of the gap. The spin-to-surface locking provides one such gap-opening mechanism, resulting in a power-law scaling of the energy gap. Weak and strong TIs show different degrees of sensitivity to the geometry of the sample. As a noteworthy example, a strong TI nanowire of a rectangular-prism shape is shown to be more gapped than that of a weak TI of precisely the same geometry. DOI: 10.1103/PhysRevB.86.245436 PACS number(s): 73.22.-f, 73.20.At, 72.80.Sk