发表机构
Stanford University; Geballe Laboratory for Advanced Materials, Stanford University; University of Austin; University of Iowa; University of California, San Diego; University of California, Irvine; Department of Physics and Center for Advanced Nanoscience, University of California, San Diego; Department of Physics and Astronomy, University of Iowa; Department of Applied Physics, Stanford University; Department of Physics , University of Austin; Department of Physics and Astronomy, University of California, Irvine; Stanford Institute for Materials（斯坦福大学; 斯坦福大学高级材料盖博实验室; 奥斯汀大学; 爱荷华大学; 加州大学圣地亚哥分校; 加州大学尔湾分校; 加州大学圣地亚哥分校物理系与先进纳米科学中心; 爱荷华大学物理与天文系; 斯坦福大学应用物理系; 奥斯汀大学物理系; 加州大学尔湾分校物理与天文系; 斯坦福材料研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过非局域自旋塞贝克测量和微磁模拟，揭示低阻尼亚铁磁薄膜中热磁振子输运受磁场和温度抑制的微观机制，确定群速度与交换刚度为关键参数。
AI 中文摘要
热产生的磁振子使得磁性绝缘体中能够实现热驱动的自旋输运，然而控制其传播的微观机制仍知之甚少。在此，我们利用非局域自旋塞贝克几何结构，研究了低阻尼Li$_{0.5}$Al$_{1.0}$Fe$_{1.5}$O$_4$/Pt纳米器件中的热磁振子输运，该结构将磁振子输运与局部热电效应分离开来。热成像确定了位于热愈合长度之外的探测器区域，从而能够进行本征非局域测量。我们发现，热磁振子输运在远高于饱和的磁场下被强烈抑制。布里渊光散射揭示，增加磁场会降低后向体磁振子的群速度，这为观察到的磁振子自旋扩散长度减小提供了微观起源。我们进一步发现，尽管磁振子布居数增加，热磁振子输运却随温度升高而降低。微磁模拟仅在包含温度相关的交换刚度时才能重现这一行为。这些结果确定了磁振子群速度和交换刚度是控制亚铁磁薄膜中热磁振子输运的关键参数。
英文摘要
Thermally generated magnons enable heat-driven spin transport in magnetic insulators, yet the relative importance of multiple microscopic mechanisms governing their propagation remains incompletely understood. Here, we investigate thermal magnon transport in low-damping Li$_{0.5}$Al$_{1.0}$Fe$_{1.5}$O$_4$/Pt nanodevices using a nonlocal spin Seebeck geometry that separates magnon transport from local thermoelectric effects. Thermal imaging establishes a detector region outside the thermal healing length, enabling intrinsic nonlocal measurements. We find that thermal magnon transport is strongly suppressed by magnetic fields far above saturation, and further that thermal magnon transport decreases with increasing temperature despite an increasing magnon population. Brillouin light scattering reveals the key microscopic mechanism driving this effect: increasing field reduces the group velocity of backward volume magnons, directly reducing the magnon spin diffusion length. Micromagnetic simulations reproduce this behavior only when a temperature-dependent exchange stiffness is included. These results identify magnon group velocity and exchange stiffness as key parameters governing thermal magnon transport in ferrimagnetic thin films.
