论文标题
拓扑Weyl木元素和分层蜂窝铁磁体中的热厅效应
Topological Weyl magnons and thermal Hall effect in layered honeycomb ferromagnets
论文作者
论文摘要
在这项工作中，我们研究了ABC堆叠蜂窝晶格中三维铁磁体的拓扑特性和镁厅效应，这是由最近对CRI $ _3 $的无弹性中子散射研究的动机。我们表明，磁杆分支的镁带结构和CHERN数字受到层间耦合$ J_C $的显着影响，此外，与其他作者相比，ABC堆叠的质量不同。最低的少磁条带的非平凡的Chern数量通过每个蜂窝层中的下一个最新纽布Dzyaloshinsky-Moriya相互作用稳定，从而导致了与石墨烯的电子Haldane模型中的跳跃项相似。但是，我们还发现了几个无间隙的Weyl点，将非等效的Chern绝缘阶段分开，并根据层间耦合$ J_C $和第三个Neighbour Heisenberg互动的比率调节。我们进一步表明，磁杆带的拓扑特征导致非零的热霍尔电导率，其符号和大小取决于$ j_c $和层内耦合。由于层间耦合强度$ j_c $可以通过向诸如CRI $ _3 $之类的准2D材料施加压力来轻松调节，因此这为在实验中提供了调整镁热厅效应的潜在途径。
In this work, we study the topological properties and magnon Hall effect of a three-dimensional ferromagnet in the ABC stacking honeycomb lattice, motivated by the recent inelastic neutron scattering study of CrI$_3$. We show that the magnon band structure and Chern numbers of the magnon branches are significantly affected by the interlayer coupling $J_c$, which moreover has a qualitatively different effect in the ABC stacking compared to the AA stacking adopted by other authors. The nontrivial Chern number of the lowest magnon band is stabilized by the next-nearest-neighbour Dzyaloshinsky-Moriya interaction in each honeycomb layer, resulting in the hopping term similar to that in the electronic Haldane model for graphene. However, we also find several gapless Weyl points, separating the non-equivalent Chern insulating phases, tuned by the ratio of the interlayer coupling $J_c$ and the third-neighbour Heisenberg interaction $J_3$. We further show that the topological character of magnon bands results in non-zero thermal Hall conductivity, whose sign and magnitude depend on $J_c$ and the intra-layer couplings. Since the interlayer coupling strength $J_c$ can be easily tuned by applying pressure to the quasi-2D material such as CrI$_3$, this provides a potential route to tuning the magnon thermal Hall effect in an experiment.
