The multiferroic ferrimagnet Cu$_2$OSeO$_3$ with a chiral crystal structure attracted a lot of recent attention due to the emergence of magnetic skyrmion order in this material. Here, the topological properties of its magnon excitations are systematically investigated by linear spin-wave theory and inelastic neutron scattering. When considering Heisenberg exchange interactions only, two degenerate Weyl magnon nodes with topological charges $\pm$2 are observed at high-symmetry points. Each Weyl point splits into two as the symmetry of the system is further reduced by including into consideration the nearest-neighbor Dzyaloshinsky-Moriya interaction, crucial for obtaining an accurate fit to the experimental spin-wave spectrum. The predicted topological properties are verified by surface state and Chern number analysis. Additionally, we predict that a measurable thermal Hall conductivity can be associated with the emergence of the Weyl points, the position of which can be tuned by changing the crystal symmetry of the material.
Emergence of a hidden-order phase well below the charge density wave transition in a topological Weyl semimetal (TaSe$_4$)$_2$I
Indian Association for the Cultivation of Science（印度科学文化研究所）；S. N. Bose National Centre for Basic Sciences（S.N. 玻色基础科学国家中心）；National Institute of Science Education and Research Bhubaneswar（布巴内斯瓦尔国立科学教育研究中心）；Birla Institute of Technology and Science, Pilani-Dubai Campus（比拉理工学院，迪拜校区）
Staged emergence of anomalous Hall transport in a correlated uranium Weyl semimetal
Idaho National Laboratory（爱达荷国家实验室）；Uppsala University（乌普萨拉大学）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Harvard University（哈佛大学）；Institute of Low Temperature and Structure Research, Polish Academy of Sciences（波兰科学院低温与结构研究所）
Prediction of Double-Weyl Points in the Iron-Based Superconductor CaKFe$_4$As$_4$
采用相结合的对称性分析，低能量建模，从头计算模拟，我们预测的磁场诱导Weyl点接近费米能级的存在下，在CaKFe $_4$作为$_4$。根据磁场和自旋轨道耦合的相对强度，外尔费米子可以携带$\pm1$或$\pm2$的拓扑电荷，使得CaKFe $_4$ As $_4$成为罕见的双外尔半金属。我们进一步预测这些外尔点的实验表现，无论是在体属性，如异常霍尔效应，并在表面性能，如出现突出的费米弧。由于CaKFe $_4$ As $_4$在30 K以下表现出非常规的全能隙超导性，我们的发现为研究Weyl费米子与超导性之间的相互作用开辟了一条新的途径。
Interface and Strain Control of Emergent Weyl Semimetallic Phase in SrNbO$_{3}$/LaFeO$_{3}$ Heterostructures
Institute of Physics, Bhubaneswar（布巴内斯瓦尔物理研究所）；Homi Bhabha National Institute（霍米·巴巴国立研究所）；Center for Atomistic Modelling and Materials Design, Indian Institute of Technology Madras（马德拉斯印度理工学院原子建模与材料设计中心）；Condensed Matter Theory and Computational Lab, Department of Physics, Indian Institute of Technology Madras（马德拉斯印度理工学院物理系凝聚态理论与计算实验室）；Laboratoire Albert Fert, CNRS, Thales, Université Paris-Saclay（阿尔伯特·费特实验室，法国国家科学研究中心，泰雷兹，巴黎萨克雷大学）；School of Basic Sciences, Indian Institute of Technology Bhubaneswar（布巴内斯瓦尔印度理工学院基础科学学院）；School of Physical Sciences, National Institute of Science Education and Research（国立科学教育与研究学院物理科学学院）；Peter Grünberg Institute, Forschungszentrum Jülich（于利希研究中心彼得·格林伯格研究所）；Department of Physics, Indian Institute of Science Bangalore（班加罗尔印度理工学院物理系）
Floquet-Weyl states at one-photon resonances in three-dimensional topological insulators
The University of Tokyo（东京大学）；Tokyo University of Science（东京理科大学）；RIKEN Center for Emergent Matter Science (CEMS)（理化学研究所 物质创造科学研究中心）；Hiroshima University（广岛大学）
Visualizing superconductivity in an inversion-symmetry-broken doped Weyl semimetal
外尔半金属MoTe $_2$为研究外尔物理和超导性之间的相互作用提供了一个难得的机会。最近的研究发现，Se的掺杂可以提高超导体的超导电性，但抑制了Weyl态出现所必需的Td结构相。到目前为止，还没有建立一个微观的理解可能共存的增强超导性和Td相。本文利用扫描隧道显微镜（STM）研究了一种最佳掺杂的新型超导体MoTe $_{1.85}$ Se $_{0.15}$，其体相温度为1.5K。利用准粒子干涉成像技术，我们确定了超导体整体共存的反转对称性破缺的低温Td相的存在。一致地，我们发现从上临界场和涡旋附近态密度的衰减中提取的超导相干长度远大于现有的掺杂剂引起的化学无序的特征长度尺度。我们发现MoTe $_{1.85}$ Se $_{0.15}$中的Weyl半金属正常相具有强的超导电性，这使其成为实现拓扑超导电性的一个有希望的候选者。
Higher-order Weyl nodes driven by helical magnetic order in EuAgAs
Agency for Science, Technology and Research (A*STAR)（科学技术研究局）；Centre for Quantum Technologies, National University of Singapore（新加坡国立大学量子科技中心）；Hunan Normal University（湖南师范大学）；University of Oxford（牛津大学）；Institut Laue-Langevin（朗之万研究所）；Diamond Light Source（钻石光源）；École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）；University of Macau（澳门大学）
