Evidence of topological boundary modes with topological nodal-point superconductivity
Evidence of topological boundary modes with topological nodal-point superconductivity
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DOI：
10.1038/s41567-021-01376-z
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发表时间：
2021-10-25
期刊：
影响因子：
19.6
通讯作者：
Beidenkopf, Haim
中科院分区：
文献类型：
--
作者：
Nayak, Abhay Kumar;Steinbok, Aviram;Beidenkopf, Haim
扫描隧道显微镜为自然界过渡金属二硫属化物材料的拓扑超导性提供了证据，拓扑超导体是拓扑保护量子计算和信息处理的重要组成部分。虽然在异质结构中已经报道了拓扑超导性的特征，但是本征拓扑超导体的材料实现是相当罕见的。在这里，我们使用扫描隧道光谱研究的过渡金属二硫属化物4 Hb-TaS 2的超导1H-TaS 2层与强关联1 T-TaS 2层的交错，并找到拓扑表面超导性的存在的光谱证据。这些包括沿沿着1H层终端以及在1 T层终端下运行的边缘模式，其中它们在具有不同拓扑性质的超导区域之间分离。我们还观察到零偏置状态的签名涡核。所有的边界模式表现出晶体学各向异性，其中连同一个有限的间隙中的状态密度在整个1H层暗示的拓扑的临界点超导状态的存在。我们的理论模型将这种现象归因于轨道间配对通道，该通道需要表面镜像对称性破缺和强相互作用的组合。因此，它暗示了在天然化合物中实现的拓扑超导状态。
Scanning tunnelling microscopy provides evidence for topological superconductivity in a naturally occurring transition metal dichalcogenide material.Topological superconductors are an essential component for topologically protected quantum computation and information processing. Although signatures of topological superconductivity have been reported in heterostructures, material realizations of intrinsic topological superconductors are rather rare. Here we use scanning tunnelling spectroscopy to study the transition metal dichalcogenide 4Hb-TaS2 that interleaves superconducting 1H-TaS2 layers with strongly correlated 1T-TaS2 layers, and find spectroscopic evidence for the existence of topological surface superconductivity. These include edge modes running along the 1H-layer terminations as well as under the 1T-layer terminations, where they separate between superconducting regions of distinct topological nature. We also observe signatures of zero-bias states in vortex cores. All the boundary modes exhibit crystallographic anisotropy, which-together with a finite in-gap density of states throughout the 1H layers-allude to the presence of a topological nodal-point superconducting state. Our theoretical modelling attributes this phenomenology to an inter-orbital pairing channel that necessitates the combination of surface mirror symmetry breaking and strong interactions. It, thus, suggests a topological superconducting state realized in a natural compound.