发表机构
University of Konstanz; Université de Bretagne Occidentale（康斯坦茨大学; 布列塔尼西方大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文利用飞秒噪声相关光谱，在时域上定量测量了铋取代钇铁石榴石中热激发和相干磁振子的数量，通过建模提取磁振子数，为非线性条件下磁振子模式的光学层析成像开辟了新途径。
AI 中文摘要
精确了解磁振子的总数，包括相干和非相干（例如热）激发，对于基础自旋波物理学的进展和下一代磁振子器件的开发至关重要。特别是，量化磁振子是理解磁振子输运现象、非线性区域或超快磁化动力学的关键。通常，非相干磁振子通过频域技术来探测，这些技术缺乏超快过程所需的时间分辨率，而超快时域方法通常仅对相干动力学敏感。在本工作中，我们证明了飞秒噪声相关光谱能够对由自由运行微波驱动的铋取代钇铁石榴石中的热激发和相干激发磁振子模式进行完全定量的时域测量。我们通过模拟样品的磁振子能带结构、磁光响应函数以及实验中使用的光斑尺寸来建模实验数据并提取磁振子数量。我们的分析建立了磁振子模式计算与实验可测量的磁性之间的联系，并可靠地再现了不同实验条件下磁光相关信号的波形和幅度。这些结果为在非线性或非平衡条件下对磁振子模式进行光学层析成像开辟了新途径，并可轻松扩展用于研究其他凝聚态系统中的超快非相干动力学。
英文摘要
Precise knowledge of the total number of magnons, including both coherent and incoherent (e.g. thermal) excitations, is imperative for the advancement of fundamental spin-wave physics and the development of next-generation magnonic devices. In particular, quantifying magnons is key to understanding magnon transport phenomena, the nonlinear regime, or ultrafast magnetization dynamics. Typically, incoherent magnons are accessed by frequency-domain techniques, which lack the temporal resolution required for ultrafast processes, while ultrafast time-domain methods are generally sensitive only to the coherent dynamics. In this work, we demonstrate that femtosecond noise correlation spectroscopy enables a fully quantitative, time-domain measurement of both thermal and coherently excited magnon modes in bismuth-substituted yttrium iron garnet driven by a free-running microwave. We model the experimental data and extract the magnon number by simulating the magnon band structure of the sample, the magneto-optical response function, and the optical spot size used in the experiment. Our analysis establishes a connection between magnon mode calculations and experimentally accessible magnetic properties and fiducially reproduces the waveform and amplitude of the magneto-optical correlation signal for different experimental conditions. These results open a new pathway towards the optical tomography of magnon modes in non-linear or non-equilibrium conditions and can be readily extended to study ultrafast incoherent dynamics in other condensed matter systems.
