标题： 这带给我们一个外尔：一种具有点费米表面的半金属外尔铁磁体的合成 显示英文标题

标题： This took us a Weyl: synthesis of a semimetallic Weyl ferromagnet with point Fermi surface

摘要： 由涌现的拓扑费米子主导的量子材料已成为物理学的基石。 石墨烯中的狄拉克费米子构成了莫尔量子物质的基础，而磁性拓扑绝缘体中的狄拉克费米子促成了量子反常霍尔效应的发现。 相比之下，很少有材料的电磁响应是由涌现的外尔费米子主导的。 几乎所有已知的外尔材料都是高度金属性的，并主要由不相关的常规电子所支配。 在这里，我们理论上预测并在实验中观察到一种半金属外尔铁磁体，其化学式为范德华力 (Cr,Bi)$_2$Te$_3$。 在输运性质中，我们发现了一个记录的体反常霍尔角$> 0.5$，以及非金属导电性，这一 regime 与传统铁磁体显著不同。 结合对称性分析，我们的数据表明一个由两个外尔点组成的半金属费米面，其线性尺寸的块体布里渊区分离度极大，$> 75\%$，且没有其他电子态。 利用最先进的晶体合成技术，我们广泛调节了电子结构，使我们能够湮灭外尔态，并可视化一个独特的拓扑相图，该图展示了广泛的陈绝缘体、外尔半金属和磁性半导体区域。 我们对外尔半金属铁磁体的观察为新型相关态和非线性现象提供了途径，同时也为零磁场下的外尔自旋电子学和光学器件提供了可能。 显示英文摘要

摘要： Quantum materials governed by emergent topological fermions have become a cornerstone of physics. Dirac fermions in graphene form the basis for moir\'e quantum matter, and Dirac fermions in magnetic topological insulators enabled the discovery of the quantum anomalous Hall effect. In contrast, there are few materials whose electromagnetic response is dominated by emergent Weyl fermions. Nearly all known Weyl materials are overwhelmingly metallic, and are largely governed by irrelevant, conventional electrons. Here we theoretically predict and experimentally observe a semimetallic Weyl ferromagnet in van der Waals (Cr,Bi)$_2$Te$_3$. In transport, we find a record bulk anomalous Hall angle $> 0.5$ along with non-metallic conductivity, a regime sharply distinct from conventional ferromagnets. Together with symmetry analysis, our data suggest a semimetallic Fermi surface composed of two Weyl points, with a giant separation $> 75\%$ of the linear dimension of the bulk Brillouin zone, and no other electronic states. Using state-of-the-art crystal synthesis techniques, we widely tune the electronic structure, allowing us to annihilate the Weyl state and visualize a unique topological phase diagram exhibiting broad Chern insulating, Weyl semimetallic and magnetic semiconducting regions. Our observation of a semimetallic Weyl ferromagnet offers an avenue toward novel correlated states and non-linear phenomena, as well as zero-magnetic-field Weyl spintronic and optical devices.