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arXiv 2202.08424cond-mat.mes-hallcond-mat.str-el
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范德华蜂窝铁磁体中磁振子的高阶拓扑相

Higher-order Topological Phases of Magnons in van der Waals Honeycomb Ferromagnets

Yun-Mei Li, Ya-Jie Wu, Xi-Wang Luo, Yongwei Huang, Kai Chang

摘要:

我们从理论上提出了一种二阶拓扑磁振子绝缘体,它是由具有反铁磁层间耦合的范德华蜂窝铁磁体堆叠而成。该系统具有Z $_{2}$拓扑相,并受到伪时间反演对称性(PTRS)的保护。易平面各向异性项破坏PTRS并破坏拓扑相位。然而,它尊重磁二重旋转对称性,这保护了双层中的角模和沿堆叠方向的铰链模的二阶拓扑相位。此外,引入的交错层间耦合建立Z $_{2}$ $\times$ Z拓扑结构,产生携带非零陈数的带隙拓扑表面模式。因此,手征铰链模式沿着长方体几何形状中的水平铰链传播,并且对紊乱是鲁棒的。我们的工作将范德华平台中的高阶拓扑和磁振子联系起来,并可用于构造拓扑磁振子器件。

英文摘要:

We theoretically propose a second-order topological magnon insulator by stacking the van der Waals honeycomb ferromagnets with antiferromagnetic interlayer coupling. The system exhibits Z$_{2}$ topological phase, protected by pseudo-time-reversal symmetry (PTRS). An easy-plane anisotropy term breaks PTRS and destroys the topological phase. Nevertheless, it respects a magnetic two-fold rotational symmetry which protects a second-order topological phase with corner modes in bilayer and hinge modes along stacking direction. Moreover, an introduced staggered interlayer coupling establishes a Z$_{2}$$\times$Z topology, giving rise to gapped topological surface modes carrying non-zero Chern numbers. Consequently, chiral hinge modes propagate along the horizontal hinges in a cuboid geometry and are robust against disorders. Our work bridges the higher-order topology and magnons in van der Waals platforms, and could be used for constructing topological magnonic devices.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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