National Laboratory of Solid State Microstructures, Department of Physics, School of Electronic Science and Engineering, Nanjing University, Nanjing, PR China.
Sci Rep. 2012;2:595. doi: 10.1038/srep00595. Epub 2012 Aug 22.
The universal conductance fluctuations (UCFs), one of the most important manifestations of mesoscopic electronic interference, have not yet been demonstrated for the two-dimensional surface state of topological insulators (TIs). Even if one delicately suppresses the bulk conductance by improving the quality of TI crystals, the fluctuation of the bulk conductance still keeps competitive and difficult to be separated from the desired UCFs of surface carriers. Here we report on the experimental evidence of the UCFs of the two-dimensional surface state in the bulk insulating Bi2Te2Se microflakes. The solely-B⊥-dependent UCF is achieved and its temperature dependence is investigated. The surface transport is further revealed by weak antilocalizations. Such survived UCFs of the surface states result from the limited dephasing length of the bulk carriers in ternary crystals. The electron-phonon interaction is addressed as a secondary source of the surface state dephasing based on the temperature-dependent scaling behavior.
普遍电导涨落（UCFs）是介观电子干涉的最重要表现之一，但尚未在拓扑绝缘体（TIs）的二维表面态中得到证实。即使通过提高 TI 晶体的质量来精细地抑制体电导，体电导的涨落仍然具有竞争力，并且难以与表面载流子的期望 UCFs 分离。在这里，我们报告了在块状绝缘 Bi2Te2Se 微片中二维表面态的 UCFs 的实验证据。实现了仅与 B⊥ 相关的 UCF，并研究了其温度依赖性。通过弱反局域进一步揭示了表面输运。这种来自三元晶体中体载流子有限退相长度的表面态幸存的 UCFs。基于温度相关的标度行为，电子-声子相互作用被认为是表面态退相的次要来源。
