Exceptional points as signatures of dynamical magnetic phase transitions
Exceptional points as signatures of dynamical magnetic phase transitions
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DOI：
10.1103/physrevb.107.l100402
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发表时间：
2023-03-06
影响因子：
3.7
通讯作者：
Flebus, Benedetta
中科院分区：
文献类型：
--
作者：
Deng, Kuangyin;Li, Xin;Flebus, Benedetta
非厄米系统最令人着迷和困惑的一个方面是它们的谱简并性，即异常点（EPs），在异常点处特征值和特征向量合并形成缺陷状态空间。虽然耦合磁系统是EPs的天然宿主，但在EPs附近的线性和非线性自旋动力学之间的关系仍然相对未被探索。本文从理论上研究了易平面磁双层层在异常点附近的自旋动力学。我们证明了内在耗散自旋动力学和外部驱动之间的相互作用可以产生丰富的动态相图。特别地，我们发现，在反铁磁耦合的双层中，在EPs包围的区域中出现了一个周期振荡的动力学相。我们的研究结果不仅为探测磁性EPs和具有大振幅振荡的工程磁性纳米振荡器提供了途径，而且揭示了非线性系统中异常点与动态相变之间的关系。
One of the most fascinating and puzzling aspects of non-Hermitian systems is their spectral degeneracies, i.e., exceptional points (EPs), at which both eigenvalues and eigenvectors coalesce to form a defective state space. While coupled magnetic systems are natural hosts of EPs, the relation between the linear and nonlinear spin dynamics in the proximity of EPs remains relatively unexplored. Here we theoretically investigate the spin dynamics of easy-plane magnetic bilayers in the proximity of exceptional points. We show that the interplay between the intrinsically dissipative spin dynamics and external drives can yield a rich dynamical phase diagram. In particular, we find that, in antiferromagnetically coupled bilayers, a periodic oscillating dynamical phase emerges in the region enclosed by EPs. Our results not only offer a pathway for probing magnetic EPs and engineering magnetic nano-oscillators with large-amplitude oscillations, but also uncover the relation between exceptional points and dynamical phase transitions in systems displaying nonlinearities.