Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
Nat Commun. 2017 Jul 11;8:16071. doi: 10.1038/ncomms16071.
Study of the dephasing in electronic systems is not only important for probing the nature of their ground states, but also crucial to harnessing the quantum coherence for information processing. In contrast to well-studied conventional metals and semiconductors, it remains unclear which mechanism is mainly responsible for electron dephasing in three-dimensional topological insulators (TIs). Here, we report on using weak antilocalization effect to measure the dephasing rates in highly tunable (Bi,Sb)Te thin films. As the transport is varied from a bulk-conducting regime to surface-dominant transport, the dephasing rate is observed to evolve from a linear temperature dependence to a sublinear power-law dependence. Although the former is consistent with the Nyquist electron-electron interactions commonly seen in ordinary 2D systems, the latter leads to enhanced electron dephasing at low temperatures and is attributed to the coupling between the surface states and the localized charge puddles in the bulk of 3D TIs.
电子系统的退相研究不仅对于探测其基态性质非常重要，而且对于利用量子相干进行信息处理也至关重要。与研究充分的传统金属和半导体不同，三维拓扑绝缘体（TI）中电子退相的主要机制尚不清楚。在这里，我们报告了使用弱反局域效应来测量在高度可调谐（Bi，Sb）Te 薄膜中的退相速率。随着输运从体导电态转变为表面主导输运，退相速率从线性温度依赖性演变为亚线性幂律依赖性。尽管前者与普通二维系统中常见的奈奎斯特电子-电子相互作用一致，但后者导致低温下电子退相增强，这归因于表面态与三维 TI 体中的局域电荷液滴之间的耦合。
