Choi Yong-Bin, Xie Yingming, Chen Chui-Zhen, Park Jinho, Song Su-Beom, Yoon Jiho, Kim B J, Taniguchi Takashi, Watanabe Kenji, Kim Jonghwan, Fong Kin Chung, Ali Mazhar N, Law Kam Tuen, Lee Gil-Ho
Department of Physics, Pohang University of Science and Technology, Pohang, Republic of Korea.
Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
Nat Mater. 2020 Sep;19(9):974-979. doi: 10.1038/s41563-020-0721-9. Epub 2020 Jul 6.
Td-WTe (non-centrosymmetric and orthorhombic), a type-II Weyl semimetal, is expected to have higher-order topological phases with topologically protected, helical one-dimensional hinge states when its Weyl points are annihilated. However, the detection of these hinge states is difficult due to the semimetallic behaviour of the bulk. In this study, we have spatially resolved the hinge states by analysing the magnetic field interference of the supercurrent in Nb-WTe-Nb proximity Josephson junctions. The Josephson current along the a axis of the WTe crystal, but not along the b axis, showed a sharp enhancement at the edges of the junction, and the amount of enhanced Josephson current was comparable to the upper limits of a single one-dimensional helical channel. Our experimental observations suggest a higher-order topological phase in WTe and its corresponding anisotropic topological hinge states, in agreement with theoretical calculations. Our work paves the way for the study of hinge states in topological transition-metal dichalcogenides and analogous phases.
Td-WTe（非中心对称且正交晶系）是一种II型外尔半金属，当其外尔点湮灭时，预计会具有高阶拓扑相以及受拓扑保护的螺旋一维棱态。然而，由于体材料的半金属行为，这些棱态的检测较为困难。在本研究中，我们通过分析Nb-WTe-Nb近邻约瑟夫森结中超电流的磁场干涉，在空间上分辨出了棱态。沿WTe晶体a轴而非b轴的约瑟夫森电流在结的边缘处显示出急剧增强，且增强的约瑟夫森电流量与单个一维螺旋通道的上限相当。我们的实验观察结果表明WTe中存在高阶拓扑相及其相应的各向异性拓扑棱态，这与理论计算结果一致。我们的工作为研究拓扑过渡金属二硫属化物中的棱态及类似相铺平了道路。
