Signatures of nontopological patches on the surface of topological insulators
Signatures of nontopological patches on the surface of topological insulators
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DOI：
10.1103/physrevb.105.035128
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发表时间：
2021-08
影响因子：
3.7
通讯作者：
Tamoghna Barik;J. Sau
中科院分区：
文献类型：
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作者：
Tamoghna Barik;J. Sau
理论和实验都表明，层状FeTe0.55Se0.45(FTS)超导体中的非平凡拓扑强烈依赖于Te的浓度。受此以及合金无序引起的Te波动的激励，我们开发了一个简单的分层模型，用于描述拓扑平凡的磁区渗透到样品中的情况。我们将这一阶段称为拓扑域无序，并研究了这一阶段可用扫描隧道谱(STS)测量的拓扑表面态的局域密度(LDOS)。我们发现，表面上没有拓扑表面态的拓扑平凡的区域，看起来就像是被增强了的LDOS的域壁所包围的受抑制的LDOS区域。此外，我们表明，研究STS的能量依赖性应该允许我们将表面的拓扑微不足道的部分与其他形式的无序区分开来。最后，我们讨论了这种拓扑表面态的局域消失对于观测涡旋中的Majorana模的意义。
The non-trivial topology in the layered FeTe0.55Se0.45 (FTS) superconductor has been suggested by both theory and experiment to be strongly dependent on the Te concentration. Motivated by this together with the Te fluctuations expected from alloy disorder, we develop a simple layered model for a strong topological insulator that allows us to describe a scenario where topologically trivial domains permeate the sample. We refer to such a phase as topological domain disordered and study the local density (LDOS) of the topological surface states that can be measured using scanning tunneling spectroscopy (STS) in this phase. We find that topologically trivial domains on the surface, where one would expect the topological surface state to be absent, appear as regions of suppressed LDOS surrounded by domain walls with enhanced LDOS. Furthermore, we show that studying the energy dependence of the STS should allow us to distinguish the topologically trivial parts of the surface from other forms of disorder. Finally, we discuss implications of such local disappearance of the topological surface states for the observation of Majorana modes in vortices.