Nodal-line semimetals (NLSMs) contain Dirac-Weyl-type band-crossing nodes extending into shapes of lines, loops, and chains in the reciprocal space, leading to band topology and transport responses. Robust NLSMs against spin-orbit coupling typically occur in three-dimensional and in-plane isotropic materials which have more symmetry operations to protect the line nodes of band crossing, while the possibilities in exfoliatable materials with in-plane anisotropy are rarely discussed. Here, we demonstrate a robust NLSM phase in an exfoliatable in-plane anisotropic nonmagnetic semimetal $\mathrm{TaNi}{\mathrm{Te}}_5$. Combining angle-resolved photoemission spectroscopy measurements and first-principles calculations, we reveal multiple Dirac-type nodal lines with fourfold degeneracy in $\mathrm{TaNi}{\mathrm{Te}}_5$. Our findings suggest rich physics in structurally anisotropic topological materials and call for further functional exploitation based on them.

中文翻译：

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面内各向异性半金属TaNiTe5中的多条狄拉克节点线

节点线半金属 (NLSM) 包含 Dirac-Weyl 型带交叉节点，在互易空间中延伸为线、环和链的形状，导致带拓扑和传输响应。抗自旋轨道耦合的鲁棒 NLSM 通常出现在三维和面内各向同性材料中，这些材料具有更多的对称操作以保护带交叉的线节点，而很少讨论具有面内各向异性的可剥离材料的可能性。在这里，我们在可剥离的面内各向异性非磁性半金属中展示了稳健的 NLSM 相$\mathrm{钽镍}{特}_5$. 结合角分辨光电子能谱测量和第一性原理计算，我们揭示了多个狄拉克型节点线在$\mathrm{钽镍}{特}_5$. 我们的研究结果表明结构各向异性拓扑材料具有丰富的物理特性，并呼吁基于它们进行进一步的功能开发。