Physikalisches Institut (EP3) , Universität Würzburg , Am Hubland, 97074 Würzburg , Germany.
Laboratoire Pierre Aigrain, Ecole Normale Supériere, PSL Research University, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, CNRS , 24 rue Lhomond , 75005 Paris , France.
Nano Lett. 2018 Aug 8;18(8):4831-4836. doi: 10.1021/acs.nanolett.8b01405. Epub 2018 Jul 10.
The topic of two-dimensional topological insulators has blossomed after the first observation of the quantum spin Hall (QSH) effect in HgTe quantum wells. However, studies have been hindered by the relative fragility of the edge states. Their stability has been a subject of both theoretical and experimental investigation in the past decade. Here, we present a new generation of high quality (Cd,Hg)Te/HgTe-structures based on a new chemical etching method. From magnetotransport measurements on macro- and microscopic Hall bars, we extract electron mobilities μ up to about 400 × 10 cm/(V s), and the mean free path λ becomes comparable to the sample dimensions. The Hall bars show quantized spin Hall conductance, which is remarkably stable up to 15 K. The clean and robust edge states allow us to fabricate high quality side-contacted Josephson junctions, which are significant in the context of topological superconductivity. Our results open up new avenues for fundamental research on QSH effect as well as potential applications in spintronics and topological quantum computation.
二维拓扑绝缘体的研究在 HgTe 量子阱中首次观测到量子自旋霍尔（QSH）效应后蓬勃发展。然而，由于边缘态相对脆弱，研究受到了阻碍。在过去的十年中，它们的稳定性一直是理论和实验研究的主题。在这里，我们提出了一种基于新化学刻蚀方法的新一代高质量（Cd，Hg）Te/HgTe 结构。通过对宏观和微观霍尔条的输运测量，我们提取出电子迁移率μ高达约 400×10cm/（V s），平均自由程 λ变得与样品尺寸相当。霍尔条显示出量子自旋霍尔电导率，在 15 K 下表现出显著的稳定性。清洁和稳健的边缘态使我们能够制造高质量的侧面接触约瑟夫森结，这在拓扑超导中具有重要意义。我们的结果为 QSH 效应的基础研究以及自旋电子学和拓扑量子计算的潜在应用开辟了新的途径。
