Fu Zhen-Guo, Zhang Ping, Chen Mu, Wang Zhigang, Zheng Fa-Wei, Lin Hai-Qing
Beijing Computational Science Research Center, Beijing 100084, China.
1] Beijing Computational Science Research Center, Beijing 100084, China [2] Institute of Applied Physics and Computational Mathematics, Beijing 100088, China.
Sci Rep. 2014 Jul 2;4:5544. doi: 10.1038/srep05544.
The peculiar nature of topological surface states, such as absence of backscattering, weak anti-localization, and quantum anomalous Hall effect, has been demonstrated mainly in bulk and film of topological insulator (TI), using surface sensitive probes and bulk transport probes. However, it is equally important and experimentally challenging to confine massless Dirac fermions with nano-steps on TI surfaces. This potential structure has similar ground with linearly-dispersed photons in Fabry-Pérot resonators, while reserving fundamental differences from well-studied Fabry-Pérot resonators and quantum corrals on noble metal surfaces. In this paper, we study the massless Dirac fermions confined within steps along the x (Γ-K) or y (Γ-M) direction on the TI surface, and the Fabry-Pérot-like resonances in the electronic local density of states (LDOS) between the steps are found. Due to the remarkable warping effect in the topological surface states, the LDOS confined in the step-well running along Γ-M direction exhibit anisotropic resonance patterns as compared to those in the step-well along Γ-K direction. The transmittance properties and spin orientation of Dirac fermion in both cases are also anisotropic in the presence of warping effect.
拓扑表面态的独特性质，如无背散射、弱反局域化和量子反常霍尔效应，主要是在拓扑绝缘体（TI）的体材料和薄膜中利用表面敏感探针和体输运探针得以证明。然而，在TI表面用纳米台阶来限制无质量狄拉克费米子同样重要且在实验上具有挑战性。这种潜在结构与法布里 - 珀罗谐振器中线性色散光子具有相似的基态，同时与在贵金属表面经过充分研究的法布里 - 珀罗谐振器和量子围栏存在根本差异。在本文中，我们研究了沿TI表面的x（Γ - K）或y（Γ - M）方向的台阶内限制的无质量狄拉克费米子，并发现了台阶之间电子局域态密度（LDOS）中的类法布里 - 珀罗共振。由于拓扑表面态中显著的翘曲效应，与沿Γ - K方向的台阶阱相比，沿Γ - M方向的台阶阱中限制的LDOS呈现出各向异性的共振模式。在存在翘曲效应的情况下，两种情况下狄拉克费米子的透射率特性和自旋取向也都是各向异性的。
