Controlling Selection Rules for Magnon Scattering in Nanomagnets by Spatial Symmetry Breaking
Controlling Selection Rules for Magnon Scattering in Nanomagnets by Spatial Symmetry Breaking
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DOI：
10.1103/physrevapplied.19.044087
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发表时间：
2023-04-27
影响因子：
4.6
通讯作者：
Verba，Roman
中科院分区：
文献类型：
--
作者：
Etesamirad，Arezoo;Kharlan，Julia;Verba，Roman
纳米磁体是许多现有和新兴自旋电子技术的构建模块。纳米磁体的磁化动力学通常由非线性过程主导，最近已被证明具有许多令人惊讶的特征并对应用产生深远的影响。在这里，我们开发了一个理论框架，揭示了多磁子过程的选择规则，并讨论了它们的基本机制。由于其技术相关性，我们重点关注薄椭圆纳米盘中的简并三磁振子过程来说明我们的发现。我们通过一组磁振子相互作用系数参数化选择规则，我们使用微磁模拟计算这些系数。我们假设了选择规则，并研究了它们如何被扰动改变，这些扰动打破了静态磁化配置和空间自旋波分布的对称性，并且可以通过应用偏轴或不均匀磁场来实现。我们的工作提供了对磁振子相互作用力学的唯象理解，以及从模拟和实验数据确定相互作用系数的形式。我们的结果可以作为分析自旋扭矩器件中固有的磁振子过程的指南，以提高其性能或设计用于神经形态或量子磁振子应用的纳米磁体的特定非线性响应。
Nanomagnets are the building blocks of many existing and emergent spintronic technologies. The magnetization dynamics of nanomagnets is often dominated by nonlinear processes, which have been recently shown to have many surprising features and far-reaching implications for applications. Here we develop a theoretical framework uncovering the selection rules for multimagnon processes and discuss their underlying mechanisms. For its technological relevance, we focus on the degenerate three-magnon process in thin elliptical nanodisks to illustrate our findings. We parameterize the selection rules through a set of magnon interaction coefficients which we calculate using micromagnetic simulations. We postulate the selection rules and investigate how they are altered by perturbations that break the symmetry of static magnetization configuration and spatial spin-wave profiles and that can be realized by applying off-symmetry-axis or nonuniform magnetic fields. Our work provides the phenomenological understanding of the mechanics of magnon interaction as well as the formalism for determining the interaction coefficients from simulations and experimental data. Our results serve as a guide to analyze the magnon processes inherently present in spin-torque devices in order to boost their performance or to engineer a specific nonlinear response in a nanomagnet used in a neuromorphic or quantum magnonic application.