不可约外尔半金属
Irreducible Weyl Semimetals
- State Key Laboratory of Metastable Materials Science and Technology and Hebei Key Laboratory of Microstructural Material Physics, School of Science, Yanshan University（燕山大学理学院亚稳材料科学与技术创新国家重点实验室和河北省微观结构物理重点实验室）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究提出不可约外尔半金属概念，通过磁空间群分类发现十种最小外尔节点构型，其中五种为新型拓扑相，为识别最小外尔复合体提供对称框架。
AI中文摘要：
外尔半金属（WSM）研究的一个关键目标是识别由外尔点（WPs）的最小配置构建的相，这些相为研究手性拓扑电荷的内在物理提供了最简单的环境。Pang等人[Phys. Rev. Res. 8, 033304 (2026)]近期确立了晶体学上可实现的外尔半金属可分解为16种最小“不可约外尔分子”（IWMs）的线性组合。一个基本问题仍未解决：这些不可分解的配置中，哪些本身能形成独立的晶相？在此，我们引入不可约外尔半金属（IWSMs），其中费米能级附近交叉的两条能带形成一个基本对称兼容的复合体，其完整的外尔节点配置是电荷中性的且在晶体学上不可分割。结合全部1651个磁空间群与外尔轨道多重性和能带兼容关系，我们对由晶体对称保护的二重外尔点形成的IWSMs进行分类。在16种原始清单中，仅有十种允许单拷贝实现，包括四种Pair、四种Split和两种Mixed电荷节点架构。值得注意的是，该分类揭示了五种非常规且此前未被识别的拓扑相：电荷三的Pair IWSM {3, -3}；Split IWSMs {3, -1, -1, -1}和{4, -1, -1, -1, -1}；以及Mixed IWSMs {3, 1, -2, -2}和{3, 3, -2, -2, -2}。对于所有十类，对称约束的晶格模型验证了完整的节点清单、Chern电荷和表面手性流入射。我们的结果确立了晶体不可约性作为超越单个外尔节点的相级组织原则，并为在电子、声子和光子系统中识别最小外尔复合体提供了对称分辨的框架。
英文摘要：
A key objective in Weyl-semimetal (WSM) research is to identify phases built from minimal configurations of Weyl points (WPs), which provide the simplest settings for investigating the intrinsic physics of chiral topological charges. Pang et al. [Phys. Rev. Res. 8, 033304 (2026)] recently established that crystallographically realizable WSMs can be decomposed into linear combinations of 16 minimal "irreducible Weyl molecules" (IWMs). A fundamental question remains unresolved: which of these non-decomposable configurations can themselves form standalone crystalline phases? Here we introduce irreducible Weyl semimetals (IWSMs), in which two bands crossing near the Fermi level form an elementary symmetry-compatible complex whose complete Weyl-node configuration is charge neutral and crystallographically indivisible. Combining all 1651 magnetic space groups with Weyl-orbit multiplicities and band-compatibility relations, we classify IWSMs formed by crystalline-symmetry-protected twofold WPs. Only ten of the sixteen primitive inventories admit one-copy realizations, comprising four Pair, four Split, and two Mixed charge-node architectures. Remarkably, this classification uncovers five unconventional and previously unrecognized topological phases: the charge-three Pair IWSM {3, -3}; the Split IWSMs {3, -1, -1, -1}, and {4, -1, -1, -1, -1}; and the Mixed IWSMs {3, 1, -2, -2} and {3, 3, -2, -2, -2}. For all ten classes, symmetry-constrained lattice models verify the complete node inventories, Chern charges, and surface chiral-flow incidence. Our results establish crystalline irreducibility as a phase-level organizing principle beyond individual Weyl nodes and provide a symmetry-resolved framework for identifying minimal Weyl complexes in electronic, phononic, and photonic systems.
