Multitude of exceptional points in van der Waals magnets
Multitude of exceptional points in van der Waals magnets
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DOI：
10.1103/physrevb.106.214432
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发表时间：
2022-07
影响因子：
3.7
通讯作者：
Xin Li;Kuangyin Deng;B. Flebus
中科院分区：
文献类型：
--
作者：
Xin Li;Kuangyin Deng;B. Flebus
最近有几项工作解决了耦合磁系统长波长动力学中异常点（EP）的出现，即非厄米哈密顿量的光谱奇点。在这里，通过关注范德华铁磁双层的驱动磁化动力学，我们表明在第一布里渊区的延伸部分上也可能出现异常点。此外，我们证明了有效的非厄米磁振子哈密顿量，其特征值是纯实数或以复共轭对形式出现，遵循不寻常的波矢相关伪厄米性。最后，对于扶手椅和锯齿形纳米带几何形状，我们讨论了拓扑边缘态的复杂和纯真实光谱及其实验意义。
Several works have recently addressed the emergence of exceptional points (EPs), i.e., spectral singularities of non-Hermitian Hamiltonians, in the long-wavelength dynamics of coupled magnetic systems. Here, by focusing on the driven magnetization dynamics of a van der Waals ferromagnetic bilayer, we show that exceptional points can appear over extended portions of the first Brillouin zone as well. Furthermore, we demonstrate that the effective non-Hermitian magnon Hamiltonian, whose eigenvalues are purely real or come in complex-conjugate pairs, respects an unusual wavevector-dependent pseudo-Hermiticity. Finally, for both armchair and zigzag nanoribbon geometries, we discuss both the complex and purely real spectra of the topological edge states and their experimental implications.