AI 中文总结
研究磁外尔半金属中拓扑与磁性相互作用，引入单极自旋密度波态，证明其序参量特性，通过晶格模型展示不同SDW序的特征及量子几何张量特性，统一相关理解并为区分磁序提供途径及暗示拓扑自旋电子学应用。
AI 中文摘要
外尔半金属中拓扑与磁性的相互作用已成为产生新型量子相的沃土。虽然单极谐波序参量已在这些系统的超导性和电荷密度波中确立，但其自旋密度波对应物仍未被探索。本文引入了由围绕相同手性外尔节点的嵌套费米面之间的粒子 - 空穴配对产生的单极自旋密度波（SDW）态。我们证明SDW序参量继承了非平凡的配对贝里相位，并由单极谐波函数描述，其在能隙函数中展现出拓扑保护的节点结构。通过具体晶格模型表明，螺旋和摆线SDW序在能带结构、费米弧分布和表面自旋极化模式中产生不同特征，可通过自旋和角分辨光电子能谱直接分辨。值得注意的是，我们发现单极配对的量子几何张量在弱耦合极限下实现了理想量子几何，其中量子距离涨落完全由贝里曲率控制。我们的结果不仅统一了对跨配对通道单极有序态的理解，还为区分ReAlX（Re = 稀土元素，X = Si，Ge）材料中竞争磁序提供了实验途径，并暗示了在拓扑自旋电子学中的潜在应用。
英文摘要
The interplay between topology and magnetism in Weyl semimetals has recently emerged as a fertile ground for novel quantum phases. While monopole harmonic order parameters have been established for superconductivity and charge density waves in these systems, their spin density wave counterparts remain unexplored. Here we introduce monopole spin density wave (SDW) states arising from particle-hole pairing between nested Fermi surfaces enclosing Weyl nodes of the same chirality. We demonstrate that the SDW order parameter inherits a nontrivial pairing Berry phase and is described by monopole harmonic functions that exhibit topologically protected nodal structures in the gap function. Through a concrete lattice model, we show that helical and cycloidal SDW orders produce distinct signatures in band structures, Fermi arc distributions, and surface spin polarization patterns, which can be directly resolved by spin- and angle-resolved photoemission spectroscopy. Remarkably, we find that the quantum geometric tensor of the monopole pairing realizes ideal quantum geometry in the weak-coupling limit, where quantum distance fluctuations are entirely governed by Berry curvature. Our results not only unify the understanding of monopole ordered states across pairing channels but also provide experimental avenues for distinguishing competing magnetic orders in ReAlX (Re=rare earth elements, X=Si, Ge) materials and suggest potential applications in topological spintronics.
Comments9 pages, 2 figures
