Linking structures of doubly charged nodal surfaces in centrosymmetric superconductors
Linking structures of doubly charged nodal surfaces in centrosymmetric superconductors
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中心对称超导体中双电荷节点表面的连接结构
DOI：
10.1103/physrevb.103.224523
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发表时间：
2020
影响因子：
3.7
通讯作者：
Bohm
中科院分区：
文献类型：
--
作者：
Sunje Kim;D. Ryu;Bohm
在拓扑半金属和节点超导体中，占据带和未占据带之间的带交叉形成携带量子化拓扑电荷的稳定节点/线/面。特别地，在中心对称系统中，费米能量E_F的一些节点结构携带两种不同的拓扑电荷，因此它们被称为双荷节点。本文表明，三维中心对称超导体的双带电节点表面总是形成特殊的连接结构，在$E_F$以下的占位带之间形成节点或线。这种连接结构可以很自然地解释$E_F$以下节点的电荷与$E_F$节点表面的两个电荷之间的内在关系。基于附加反转$\mathcal{I}$对称性的Altland-Zirnbauer （AZ）型十重分类，即AZ$+\mathcal{I}$分类，我们给出了中心对称系统中双荷电节点连接结构的完整列表。双电荷节点的连接结构清楚地表明，不仅节点周围的局部带结构，而且全局带结构在表征无间隙拓扑相中起着至关重要的作用。
In topological semimetals and nodal superconductors, band crossings between occupied and unoccupied bands form stable nodal points/lines/surfaces carrying quantized topological charges. In particular, in centrosymmetric systems, some nodal structures at the Fermi energy $E_F$ carry two distinct topological charges, and thus they are called doubly charged nodes. Here we show that doubly charged nodal surfaces of centrosymmetric superconductors in three-dimensions always develop peculiar linking structures with nodal points or lines formed between occupied bands below $E_F$. Such linking structures can naturally explain the inherent relationship between the charge of the node below $E_F$ and the two charges of the nodal surfaces at $E_F$. Based on the Altland-Zirnbauer (AZ)-type ten-fold classification of nodes with additional inversion $\mathcal{I}$ symmetry, which is called the AZ$+\mathcal{I}$ classification, we provide the complete list of linking structures of doubly charged nodes in centrosymmetric systems. The linking structures of doubly charged nodes clearly demonstrate that not only the local band structure around the node but also the global band structure play a critical role in characterizing gapless topological phases.