Catalog of Unconventional Magnons in Collinear Magnets
Xiaobing Chen, Yuntian Liu, Pengfei Liu, Yutong Yu, Jun Ren, Jiayu Li, Ao Zhang, Qihang Liu
备注：
The manuscript contains 28 pages, 3 figures and 2 tables. The supplementary information contains 349 pages, 15 figures and 245 tables. The databases for all 1421 collinear spin space groups and the magnon band structures are provided on https://www.findspingroup.com/
Topological magnons have garnered significant interest for their potential in both fundamental research and device applications, owing to their exotic, uncharged, yet topologically protected boundary modes. However, their comprehension has been hindered by the absence of fundamental symmetry descriptions of magnetic materials, which are primarily governed by isotropic Heisenberg interactions in spin Hamiltonians. The ensuing magnon dispersions enable gapless magnon band nodes that go beyond the scenario of representation theory of the magnetic space groups (MSGs), thus referred to as unconventional magnons. Here we developed spin space group (SSG) theory to elucidate collinear magnetic configurations, classifying the 1421 collinear SSGs into four types, constructing their band representations, and providing a comprehensive tabulation of unconventional magnons, such as duodecuple points, octuple nodal lines, and charge-4 octuple points. Based on the MAGNDATA database, we identified 498 collinear magnets with unconventional magnons, among which over 200 magnon band structures were obtained by using first-principles calculations and linear spin wave theory. Additionally, we evaluated the influence of the spin-orbit coupling-induced exchange interaction in these magnets and found that more than 80% are predominantly governed by the Heisenberg interactions, indicating that SSG serves as an ideal framework for describing magnon band nodes in most 3d, 4d and half-filled 4f collinear magnets. Our work offers new pathways for exploring uncharged transports in magnonic systems, holding promise for advancements in next-generation spintronic devices.
Dispersion and lifetimes of magnons in non-collinear magnets from time dependent density functional theory
Institute for Theoretical Physics, Johannes Kepler University（约翰内斯·开普勒大学理论物理研究所）；Hamburg University of Applied Sciences（汉堡应用科学大学）；Max Planck Institute of Microstructure Physics（马克斯·普朗克微观结构物理研究所）；Donostia International Physics Center (DIPC)（圣塞巴斯蒂安国际物理中心）
利用绝缘体中的纯磁振子自旋电流进行信息传输和处理是传统电荷电流驱动自旋电子器件的一种很有前途的替代方案。焦耳加热的情况下，以及减少自旋波阻尼绝缘铁磁体已被建议，使有效的逻辑器件的实施。在基于自旋波叠加的逻辑多数门的概念验证成功之后，需要更多的组件来执行复杂的逻辑运算。一个关键的组成部分是一个开关，对应于一个传统的磁阻自旋阀。在这里，我们报告的磁化取向依赖的自旋信号检测共线磁性多层膜自旋输运的磁振子自旋电流。我们发现在Y3 Fe 5 O 12 |CoO| Co三层薄膜中，探测到的自旋信号依赖于Y3 Fe 5 O 12和Co的相对取向。这表明在我们的系统中存在自旋阀行为，其效应幅度为120%。我们证明了这种效应的可靠性，并通过温度和功率相关的测量来研究起源，表明自旋整流效应和磁性层取向相关的自旋输运效应导致测量信号。
Symmetry Enhanced Unconventional Spin Current Anisotropy in a Collinear Antiferromagnet
University of Gothenburg（哥德堡大学）；Research Institute of Electrical Communication, Tohoku University（东北大学电气通信研究所）；Indian Institute of Technology Delhi（德里印度理工学院）
Dynamical magnetic susceptibility of non-collinear magnets: A novel KKR-based ab initio scheme and its application
Institute for Theoretical Physics, Johannes Kepler University Linz（林茨约翰内斯开普勒大学理论物理研究所）；Hamburg University of Applied Sciences（汉堡应用科学大学）；Max Planck Institute of Microstructure Physics（马克斯·普朗克微结构物理研究所）；Donostia International Physics Center (DIPC)（多诺斯蒂亚国际物理中心）
Spin-waves in the collinear antiferromagnetic phase of Mn$_\bf{5}$Si$_\bf{3}$
本文结合非弹性中子散射测量和密度泛函理论计算两种独立的方法，研究了Mn $_5$ Si $_3$高温共线反铁磁相（AFM 2）中的自旋波.我们得到了它的磁基态性质和电子结构。这项研究使我们能够确定主要的磁交换相互作用和磁晶各向异性的AFM 2相的Mn $_5$ Si $_3$。此外，自旋激发谱的演变的影响下，外部磁场垂直于各向异性易轴的影响进行了研究。低能磁振子模表现出不同的磁场依赖性，这是它们不同的岁差性质的直接结果。最后，还考虑了与Dzyaloshinskiii-Moriya相互作用相关的可能影响。
Strain-driven spin-flop transition and collapse of the giant magnon gap in the bilayer iridate Sr$_3$Ir$_2$O$_7$
Ajou University（亚洲大学）
双层铱酸盐Sr $_3$ Ir $_2$ O $_7$是$c$轴共线反铁磁体，由巨大的层间赝偶极各向异性保持，而单层Sr $_2$ IrO $_4$在$ab$平面内倾斜。我们表明，从第一原理，双轴压缩的百分之几（$\varepsilon_c\approx-2.4\%$）的易轴的Sr $_3$ Ir $_2$ O $_7$到平面。一个磁模型哈密顿建立从瓦尼尔函数没有拟合参数-再现巨大的磁振子间隙的大部分，到目前为止，只知道从拟合实验-确定的机制。压缩崩溃的层间交换通道，其直的Ir-O-Ir路径减弱为弯曲的面内路径加强。洪德交换确定了各向异性的尺度，并且在$J/U\approx0.15$之外，完全消除了共线状态。这种翻转并不是一种严格的旋转-两个态的有序矩在$\varepsilon_c$交叉-它带有一个明显的指纹，因为巨大的易轴磁振子能隙坍缩成一个无隙的、类似戈德斯通的光谱。压缩应变膜，从而坐在一个变磁相边界结束在一个零温度的双临界点，一个电荷中性处理自旋轨道纠缠秩序。
A General Theory of Chiral Splitting of Magnons in Two-Dimensional Magnets
School of Materials Science and Physics, China University of Mining and Technology（中国矿业大学材料科学与工程学院）；Jiangsu Physical Science Research Center（江苏省物理科学研究中心）
Southern University of Science and Technology (SUSTech)（南方科技大学）；Quantum Science Center of Guangdong–Hong Kong–Macao Greater Bay Area (Guangdong)（粤港澳大湾区量子科学中心）
Plaid-Like Spin Splitting and Chirality of Magnon Bands in Antiferromagnetic MnTe$_2$
Sejong University（世宗大学）；Korea Advanced Institute of Science and Technology (KAIST)（韩国科学技术院）；Sungkyunkwan University（成均馆大学）；Institute of Physics, Academia Sinica（中央研究院物理研究所）
