近场自旋波成像中磁振子-磁振子干涉产生的表观零动量信号
Apparent Zero-Momentum Signals from Magnon--Magnon Interference in Near-Field Spin-Wave Imaging
- Laboratoire Albert Fert, CNRS, Thales, Université Paris-Saclay（阿尔贝·费尔特实验室，法国国家科学研究中心，泰雷兹集团，巴黎萨克雷大学）
- Lab-STICC, CNRS UMR 6285, Université de Bretagne Occidentale（STICC实验室，法国国家科学研究中心联合研究单位6285，布列塔尼西部大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文通过近场自旋波成像实验证明，表观零动量信号源于磁振子干涉，而非本征模式，并提出干涉场谱框架以识别纳米磁振子器件中的散射过程。
AI中文摘要：
相干波的空间分辨测量通常被解读为底层本征模式谱的直接映射。我们证明，在多模自旋波输运的近场成像中，这种解读是错误的。对钇铁石榴石进行的扫描氮-空位磁力测量揭示了在不存在传播自旋波模式的频率处出现显著的表观低波矢信号。通过调节探针-样品距离并模拟各向异性近场响应，我们确定其来源为直接激发的Damon-Eshbach波与缺陷或换能器散射自旋波之间的相干混合：测量信号获得了差波矢$\mathbf{k}_{\mathrm{exc}}-\mathbf{k}_{\mathrm{scat}}$处的空间傅里叶分量，即使两个组成波均携带有限动量，该差波矢也可能为零。这些结果表明，相干激发的近场谱是干涉场谱而非本征模式图，这既为识别纳米级磁振子器件中的散射过程提供了警示，也提供了框架。
英文摘要：
Spatially resolved measurements of coherent waves are commonly read as direct maps of the underlying eigenmode spectrum. We show that this interpretation fails in near-field imaging of multimode spin-wave transport. Scanning nitrogen-vacancy magnetometry of yttrium iron garnet reveals pronounced apparent low-wave-vector signals at frequencies for which no propagating spin-wave mode exists. By tuning the probe-sample distance and modeling the anisotropic near-field response, we identify their origin as coherent mixing between directly excited Damon-Eshbach waves and defect- or transducer-scattered spin waves: the measured signal acquires spatial Fourier components at the difference wave vector $\mathbf{k}_{\mathrm{exc}}-\mathbf{k}_{\mathrm{scat}}$, which can vanish even though both constituent waves carry finite momentum. These results establish that near-field spectra of coherent excitations are interferometric field spectra rather than eigenmode maps, providing both a caution and a framework for identifying scattering processes in nanoscale magnonic devices.
