Li Y W, Zheng H J, Fang Y Q, Zhang D Q, Chen Y J, Chen C, Liang A J, Shi W J, Pei D, Xu L X, Liu S, Pan J, Lu D H, Hashimoto M, Barinov A, Jung S W, Cacho C, Wang M X, He Y, Fu L, Zhang H J, Huang F Q, Yang L X, Liu Z K, Chen Y L
School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, People's Republic of China.
Department of Physics, University of Oxford, Oxford, OX1 3PU, UK.
Nat Commun. 2021 May 17;12(1):2874. doi: 10.1038/s41467-021-23076-1.
Topological superconductors (TSCs) are unconventional superconductors with bulk superconducting gap and in-gap Majorana states on the boundary that may be used as topological qubits for quantum computation. Despite their importance in both fundamental research and applications, natural TSCs are very rare. Here, combining state of the art synchrotron and laser-based angle-resolved photoemission spectroscopy, we investigated a stoichiometric transition metal dichalcogenide (TMD), 2M-WS with a superconducting transition temperature of 8.8 K (the highest among all TMDs in the natural form up to date) and observed distinctive topological surface states (TSSs). Furthermore, in the superconducting state, we found that the TSSs acquired a nodeless superconducting gap with similar magnitude as that of the bulk states. These discoveries not only evidence 2M-WS as an intrinsic TSC without the need of sensitive composition tuning or sophisticated heterostructures fabrication, but also provide an ideal platform for device applications thanks to its van der Waals layered structure.
拓扑超导体(TSCs)是一类非常规超导体,其体内存在超导能隙,边界上存在能隙内的马约拉纳态,可作为量子计算的拓扑量子比特。尽管它们在基础研究和应用中都很重要,但天然的拓扑超导体非常罕见。在此,我们结合了最先进的同步加速器和基于激光的角分辨光电子能谱技术,研究了一种化学计量比的过渡金属二硫属化物(TMD)——2M-WS₂,其超导转变温度为8.8 K(是迄今为止天然形式的所有TMD中最高的),并观测到了独特的拓扑表面态(TSSs)。此外,在超导态下,我们发现拓扑表面态获得了一个无节点的超导能隙,其大小与体内态的超导能隙相似。这些发现不仅证明了2M-WS₂是一种本征拓扑超导体,无需进行敏感的成分调整或复杂的异质结构制备,而且由于其范德华层状结构,还为器件应用提供了一个理想的平台。