发表机构
Shenzhen Research Institute of Shandong University（山东大学深圳研究院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出二阶实节点线半金属，其中一对实节点线由节点面链接，并在互穿石墨烯网络中通过第一性原理计算证实，产生铰链费米弧和鼓膜表面态，为高阶实拓扑提供新途径。
AI 中文摘要
具有实陈数和二阶边界态的实节点线（RNLs）引起了广泛关注。在以往所有报道的实现中，一条实节点线与另一条节点线相互链接，而实节点线是否能与其他类型的能带简并相链接的问题仍然悬而未决。在此，我们提出了一种二阶实节点线半金属，其中一对实节点线由一个节点面链接。我们证明，该态可以在同时具有$PT$和非辛对称$S_{2z}T$的自旋less系统中实现，其中$S_{2z}T$强制的节点面阻止了这对实节点线的湮灭。每条节点线携带非平凡的实陈数$\ u_R=1$，从而产生位于一对$PT$相关铰链上的拓扑铰链费米弧。在此构造的指导下，我们确定了互穿石墨烯网络（IGN）作为有前景的材料实现。第一性原理计算证实，一对穿越布里渊区的节点线由一个节点面链接，且每条节点线携带双重非平凡的$Z_2$电荷。IGN的体-边界对应表现为一对铰链费米弧以及鼓膜表面态。我们的工作确立了节点面作为实节点线的新型链接伙伴，并为探索碳基及其他轻元素系统中的高阶实拓扑提供了路线图。
英文摘要
Real nodal lines (RNLs) featuring real Chern numbers and second-order boundary modes have attracted widespread attention. In all previously reported realizations, an RNL is linked by another nodal line, and whether an RNL can be linked by other types of band degeneracies has remained open. Here, we propose a second-order real nodal-line semimetal in which a pair of RNLs is linked by a nodal surface. We show that this state can be realized in spinless systems with both $PT$ and nonsymmorphic $S_{2z}T$ symmetries, where the $S_{2z}T$-enforced nodal surface prevents the pair of RNLs from annihilation. Each nodal line carries a nontrivial real Chern number $ν_R=1$, giving rise to topological hinge Fermi arcs located at a pair of $PT$-related hinges. Guided by this construction, we identify the interpenetrated graphene network (IGN) as a promising material realization. First-principles calculations confirm that a pair of nodal lines traversing the Brillouin zone are linked by a nodal surface and each nodal line carries double nontrivial $Z_2$ charges. The bulk-boundary correspondence of IGN manifests as a pair of hinge Fermi arcs together with drumhead surface states. Our work establishes nodal surfaces as a new linking partner for real nodal lines and provides a roadmap for exploring higher-order real topology in carbon-based and other light-element systems.
Comments7 pages and 4 figures
