Kononov Artem, Abulizi Gulibusitan, Qu Kejian, Yan Jiaqiang, Mandrus David, Watanabe Kenji, Taniguchi Takashi, Schönenberger Christian
Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
Institute of Solid State Physics of the Russian Academy of Sciences - Chernogolovka, Moscow District, Academician Ossipyan str. 2, Chernogolovka 142432, Russia.
Nano Lett. 2020 Jun 10;20(6):4228-4233. doi: 10.1021/acs.nanolett.0c00658. Epub 2020 May 18.
WTe is a layered transitional-metal dichalcogenide (TMD) with a number of intriguing topological properties. Recently, WTe has been predicted to be a higher-order topological insulator (HOTI) with topologically protected hinge states along the edges. The gapless nature of WTe complicates the observation of one-dimensional (1D) topological states in transport due to their small contribution relative to the bulk. Here, we study the behavior of the Josephson effect in magnetic field to distinguish edge from bulk transport. The Josephson effect in few-layer WTe reveals 1D states residing on the edges and steps. Moreover, our data demonstrates a combination of Josephson transport properties observed solely in another HOTI-bismuth, including Josephson transport over micrometer distances, extreme robustness in a magnetic field, and nonsinusoidal current-phase relation (CPR). Our observations strongly suggest the topological origin of the 1D states and that few-layer WTe is a HOTI.
WTe是一种具有许多有趣拓扑性质的层状过渡金属二卤化物（TMD）。最近，WTe被预测为一种高阶拓扑绝缘体（HOTI），其沿边缘具有拓扑保护的铰链态。WTe的无隙性质使得在输运中观察一维（1D）拓扑态变得复杂，因为它们相对于体相的贡献较小。在这里，我们研究磁场中约瑟夫森效应的行为，以区分边缘输运和体相输运。少层WTe中的约瑟夫森效应揭示了存在于边缘和台阶上的一维态。此外，我们的数据展示了仅在另一种HOTI——铋中观察到的约瑟夫森输运性质的组合，包括微米距离上的约瑟夫森输运、磁场中的极强鲁棒性以及非正弦电流-相位关系（CPR）。我们的观察结果强烈表明一维态的拓扑起源，并且少层WTe是一种HOTI。
