Coexistence of topological bands and a charge density wave (CDW) in topological materials has attracted immense attention because of their fantastic properties, such as an axionic CDW, the three-dimensional quantum Hall effect, etc. In this work, the nodal-line semimetal ${\mathrm{In}}_x{\mathrm{TaS}}_2$ characterized by a CDW and superconductivity is successfully synthesized, whose structure and topological bands (two separated Weyl rings) are similar to ${\mathrm{In}}_{0.58}{\mathrm{TaSe}}_2$. A $2\times 2$ commensurate CDW is observed at low temperature in ${\mathrm{In}}_x{\mathrm{TaS}}_2$, identified by transport properties and scanning tunneling microscopy measurements. Moreover, superconductivity emerges below 0.69 K, and the anisotropy ratio of the upper critical field $[\mathrm{\Gamma }=H_{c2}^{\left|\right|ab}\left(0\right)/H_{c2}^{\left|\right|c}\left(0\right)]$ is significantly enhanced compared to 2H-${\mathrm{TaS}}_2$, which shares the same essential layer unit. According to the Lawrence-Doniach model, the enhanced $\mathrm{\Gamma }$ may be explained by the reduced effective mass in the $k_x\text{−}{k}_y$ plane, where Weyl rings locate. Therefore, this type of layered topological systems may offer a platform to investigate highly anisotropic superconductivity and to understand the extremely large upper critical field in the bulk or in the two-dimensional limit.

中文翻译：

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拓扑节点线半金属InxTaS2中增强的各向异性超导性

拓扑带的共存和拓扑材料中的电荷密度波（CDW）由于具有奇异的特性而受到了广泛的关注，例如轴键CDW，三维量子霍尔效应等。在这项工作中，节点线半金属 ${在}_X{钽}_2$ 以CDW为特征并成功合成了超导材料，其结构和拓扑带（两个分开的Weyl环）与 ${在}_{0.58}{\mathrm{钽硒}}_2$。一种$2\times 2$ 在低温下观察到相称的CDW ${在}_X{钽}_2$通过传输特性和扫描隧道显微镜测量确定。此外，在0.69 K以下出现超导，并且上临界场的各向异性比$[\mathrm{\Gamma }=H_{C2}^{\left|\right|\mathrm{一种}b}（0）/H_{C2}^{\left|\right|C}（0）]$ 相较于2H-${钽}_2$，它们共享相同的基本层单元。根据Lawrence-Doniach模型，$\mathrm{\Gamma }$ 可以用减少有效质量来解释 ${ķ}_X\text{-}{ķ}_{ÿ}$Weyl环所在的平面。因此，这种类型的分层拓扑系统可以提供一个平台来研究高度各向异性的超导性，并了解整体或二维极限中的极大的上临界场。