对称性保护的三重外尔复合物
Symmetry-protected triplet Weyl complexes
- Yanshan University（燕山大学）
- Shenzhen Research Institute of Shandong University（山东大学深圳研究院）
- The Hong Kong Polytechnic University（香港理工大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文研究三重外尔复合物（TWC）的对称性条件，发现仅{1,1,2}和{1,2,3}型TWC可实现，验证了{1,2,3}-TWC的存在，首次在DZQH-C₃₆中实现{1,1,2}-TWC拓扑半金属态。
AI中文摘要：
Nielsen-Ninomiya定理指出，外尔节点必须以相反手性成对出现以保持全局电中性。然而在晶体中，特定晶体对称性可稳定多外尔节点，规避这一对对约束，形成具有混合手性电荷的补偿型外尔复合物。这类复合物的最小构型是三重外尔复合物（TWC），恰好包含三个外尔节点。本文系统研究实现TWC所需的对称性条件，通过筛选所有1651个磁性空间群（MSG）（含无自旋和有自旋体系），明确：（i）仅允许电荷大小为{1,1,2}和{1,2,3}的TWC；（ii）{1,1,2}构型可在166个无自旋MSG和70个有自旋MSG中实现；（iii）此前未报道过的{1,2,3}-TWC可在10个无自旋和有自旋MSG中存在。我们在紧束缚模型中明确验证了{1,2,3}-TWC的存在，还首次在手性碳同素异形体DZQH-C₃₆中实现了{1,1,2}-TWC拓扑半金属态，其中三个外尔节点呈共线构型，形成特征性“S”形表面费米弧图案。本研究揭示了具有混合手性电荷的新型拓扑态，为在具体材料体系中探索其物理性质提供了指导。
英文摘要：
The Nielsen-Ninomiya theorem dictates that Weyl nodes must appear in pairs of opposite chirality to preserve global charge neutrality. However, in crystals, specific crystalline symmetries can stabilize multi-Weyl nodes, circumventing this pairwise constraint and enabling compensated Weyl complexes with mixed chiral charges. The minimal configuration of this type is a triplet Weyl complex (TWC), comprising exactly three Weyl nodes. Here, we systematically investigate the symmetry conditions required to realize TWCs. By screening all 1651 magnetic space groups (MSGs) in both spinless and spinful systems, we establish that: (i) Only TWCs with charge magnitudes of $\{1,1,2\}$ and $\{1,2,3\}$ are permitted; (ii) the $\{1,1,2\}$ configuration can be realized in 166 spinless MSGs and 70 spinful MSGs; and (iii) the $\{1,2,3\}$-TWCs, which has not been reported before, can occur in 10 MSGs for both spinless and spinful cases. We explicitly demonstrate the existence of $\{1,2,3\}$-TWC in a tight-binding model. Furthermore, we present the first electronic realization of $\{1,1,2\}$-TWC topological semimetal state in the chiral carbon allotrope DZQH-C$_{36}$, in which the three Weyl nodes form a collinear configuration, leading to a characteristic ``S''-shaped surface Fermi arc pattern. Our findings uncover novel topological states featuring mixed chiral charges and provide guidance for exploring their physics in concrete material systems.
