Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
School of Computer Science, Fudan University, Shanghai 200433, People's Republic of China.
Nat Commun. 2016 Sep 21;7:12691. doi: 10.1038/ncomms12691.
Frustrated quantum magnets not only provide exotic ground states and unusual magnetic structures, but also support unconventional excitations in many cases. Using a physically relevant spin model for a breathing pyrochlore lattice, we discuss the presence of topological linear band crossings of magnons in antiferromagnets. These are the analogues of Weyl fermions in electronic systems, which we dub Weyl magnons. The bulk Weyl magnon implies the presence of chiral magnon surface states forming arcs at finite energy. We argue that such antiferromagnets present a unique example, in which Weyl points can be manipulated in situ in the laboratory by applied fields. We discuss their appearance specifically in the breathing pyrochlore lattice, and give some general discussion of conditions to find Weyl magnons, and how they may be probed experimentally. Our work may inspire a re-examination of the magnetic excitations in many magnetically ordered systems.
受挫的量子磁体不仅提供了奇异的基态和不寻常的磁结构，而且在许多情况下还支持非常规激发。我们使用一个与物理相关的呼吸尖晶石晶格的自旋模型，讨论了反铁磁体中磁振子的拓扑线性能带交叉的存在。这些是电子系统中 Weyl 费米子的类似物，我们称之为 Weyl 磁振子。体 Weyl 磁振子意味着存在手性磁振子表面态，在有限能量下形成弧形。我们认为，这种反铁磁体提供了一个独特的例子，其中 Weyl 点可以通过施加的场在实验室中进行原位操纵。我们特别讨论了它们在呼吸尖晶石晶格中的出现，并给出了一些关于寻找 Weyl 磁振子的条件的一般讨论，以及它们如何在实验中被探测到。我们的工作可能会激发对许多磁有序系统中磁激发的重新审视。
