Power-law decay of standing waves on the surface of topological insulators
Power-law decay of standing waves on the surface of topological insulators
复制标题
拓扑绝缘体表面驻波的幂律衰减
DOI：
10.1103/physrevb.84.235447
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发表时间：
2011-12-29
影响因子：
3.7
通讯作者：
Zhu, Bang-Fen
中科院分区：
文献类型：
--
作者：
Wang, Jing;Li, Wei;Zhu, Bang-Fen
本文提出了拓扑绝缘体中由表面态沿阶边散射引起的驻波（准粒子干涉图样）的一般理论，其中表面带恒定能量轮廓上的极值点起主导作用。实验上，我们用扫描隧道显微镜测量了Bi2Te3和Bi2Se3薄膜上的局部态密度，从而对干涉图案进行了成像。观测到的驻波衰减指数与理论预测非常吻合：在Bi2Se3中，仅存在-3/2的单一衰减指数，而在具有强翘曲表面带的Bi2Te3中，随着能量的增加，其衰减指数从-3/2变化到-1/2，最后变为-1。-1/2衰减表明，由于时间反转对称性而抑制后向散射并不一定导致空间衰减速率比传统二维电子系统更快。我们的形式也能更好地解释Bi2Te3上非磁性杂质引起的驻波特征散射波矢量。
We propose a general theory on the standing waves (quasiparticle interference pattern) caused by the scattering of surface states off step edges in topological insulators in which the extremal points on the constant energy contour of surface band play a dominant role. Experimentally, we image the interference patterns on both Bi2Te3 and Bi2Se3 films by measuring the local density of states with a scanning tunneling microscope. The observed decay indices of the standing waves agree excellently with the theoretical prediction: In Bi2Se3, only a single decay index of -3/2 exists, while in Bi2Te3 with strongly warped surface band, it varies from -3/2 to -1/2 and finally to -1 as the energy increases. The -1/2 decay indicates that the suppression of backscattering due to time-reversal symmetry does not necessarily lead to a spatial decay rate faster than that in the conventional two-dimensional electron system. Our formalism can also better explain the characteristic scattering wave vectors of the standing wave caused by nonmagnetic impurities on Bi2Te3.