发表机构
Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau; Indian Institute of Technology (Indian School of Mines); Uppsala University; University of Münster（莱茵兰-普法尔茨技术大学凯泽斯劳滕-兰道分校; 印度理工学院（印度矿业学院）; 乌普萨拉大学; 明斯特大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出反对称Gilbert阻尼作为磁振子手性阻尼的新机制，无需Dzyaloshinskii-Moriya相互作用即可产生非互易阻尼，且效应约大一个数量级。
AI 中文摘要
磁振子手性阻尼指的是相对于磁振子波矢不对称的阻尼。这种非互易性此前被归因于反对称的Dzyaloshinskii-Moriya自旋相互作用。在此，我们利用线性自旋波理论和在Landau-Lifshitz-Gilbert运动方程中引入的反对称Gilbert阻尼，为磁振子手性阻尼提供了一种替代的理论解释。首先，采用矩形晶格上单子格铁磁体的最小模型，我们表明有效磁振子阻尼与系统的能量无关，包括来自Dzyaloshinskii-Moriya相互作用的贡献。考虑标量非局域Gilbert阻尼时，有效阻尼参数$\alpha_{\rm eff}$变得依赖于波矢。在长波长极限下，$\alpha_{\rm eff}$获得对$\bf{k}$的二次依赖。此外，Gilbert阻尼张量的反对称分量产生不对称（非互易）的磁振子阻尼。我们发现这种不对称性在长波长极限下对$\bf{k}$是线性的，与近期的实验一致。将分析扩展到双子格系统时，我们考虑了跨子格Gilbert阻尼。在仅存在标量Gilbert阻尼的情况下，磁振子弛豫中破坏的互易性源于Dzyaloshinskii-Moriya相互作用。相比之下，Gilbert阻尼张量的跨子格反对称分量即使将Dzyaloshinskii-Moriya相互作用参数化地设为零，也能产生非互易磁振子阻尼，为不对称自旋波弛豫提供了一种替代机制。值得注意的是，由反对称Gilbert阻尼引起的非互易性大约比由Dzyaloshinskii-Moriya相互作用引起的非互易性大一个数量级。
英文摘要
Magnon chiral damping denotes damping that is asymmetric with respect to the magnon wave vector. Such nonreciprocity has been attributed to antisymmetric Dzyaloshinskii-Moriya spin interactions. Here, we provide an alternative theoretical explanation of magnon chiral damping using linear spin-wave theory and antisymmetric Gilbert damping introduced within the Landau-Lifshitz-Gilbert equation of motion. First, employing a minimal model of a single sublattice ferromagnet on a rectangular lattice, we show that the effective magnon damping is independent of the system's energy, including contributions from Dzyaloshinskii-Moriya interactions. Considering scalar nonlocal Gilbert damping, the effective damping parameter $α_{\rm eff}$ becomes wave-vector dependent. In the long-wavelength limit, $α_{\rm eff}$ acquires a quadratic dependence on $\bf{k}$. Furthermore, the antisymmetric component of the Gilbert damping tensor gives rise to asymmetric (nonreciprocal) magnon damping. We find the asymmetry to be linear in $\bf{k}$ in the long-wavelength limit, consistent with recent experiments. Extending the analysis to a two-sublattice system, we consider cross-sublattice Gilbert damping. In the presence of only scalar Gilbert damping, broken reciprocity in magnon relaxation arises from Dzyaloshinskii-Moriya interactions. In contrast, the cross-sublattice antisymmetric component of the Gilbert damping tensor can generate nonreciprocal magnon damping even if the Dzyaloshinskii-Moriya interaction is parametrically set to zero, providing an alternative mechanism for asymmetric spin-wave relaxation. Notably, the nonreciprocity induced by antisymmetric Gilbert damping is roughly an order of magnitude larger than that arising from Dzyaloshinskii-Moriya interactions.
Comments14 pages, 6 figures
