标题： 基于毫开尔文温度下YIG-GGG异质结构中的波数相关磁损耗 显示英文标题

标题： Wavenumber-dependent magnetic losses in YIG-GGG heterostructures at millikelvin temperatures

摘要： 磁子因其固有的非线性、纳米尺度的可扩展性以及一组实验上可访问的参数，可用于调节其色散，从而在现代量子技术和混合量子系统中激发了潜在的应用。这种基于磁子的量子技术需要长的退相干时间、毫开尔文温度和最小的耗散。由于其低磁阻尼，生长在钆镓石榴石（GGG）上的铁氧体钇铁石榴石（YIG）是实现这一目标最有前途的材料。为了理解在低温下传播磁子在YIG-GGG异质结构中的磁损耗，我们通过传播自旋波谱（PSWS）测量，在4K到26mK的温度范围内研究了微米厚的YIG样品中的磁子传输。我们展示了在低温下，耗散率随波数增加的现象，这是由于与部分磁化的GGG基底的偶极耦合引起的。此外，我们观察到自旋波传输的温度依赖性减少，这归因于稀土离子的弛豫。实验结果与理论计算和微磁模拟的比较证实了低温下额外耗散通道的关键作用。我们的发现加强了对毫开尔文温度下磁子损耗的理解，这对于未来检测单个传播磁子至关重要。 显示英文摘要

摘要： Magnons have inspired potential applications in modern quantum technologies and hybrid quantum systems due to their intrinsic nonlinearity, nanoscale scalability, and a unique set of experimentally accessible parameters for manipulating their dispersion. Such magnon-based quantum technologies demand long decoherence times, millikelvin temperatures, and minimal dissipation. Due to its low magnetic damping, the ferrimagnet yttrium iron garnet (YIG), grown on gadolinium gallium garnet (GGG), is the most promising material for this objective. To comprehend the magnetic losses of propagating magnons in such YIG-GGG heterostructures at cryogenic temperatures, we investigate magnon transport in a micrometer-thick YIG sample via propagating spin-wave spectroscopy (PSWS) measurements for temperatures between 4K to 26mK. We demonstrate an increase in the dissipation rate with wavenumber at cryogenic temperatures, caused by dipolar coupling to the partially magnetized GGG substrate. Additionally, we observe a temperature-dependent decrease in spin-wave transmission, attributed to rare earth ion relaxations. The critical role of the additional dissipation channels at cryogenic temperatures is underpinned by the comparison of the experimental results with theoretical calculations and micromagnetic simulations. Our findings strengthen the understanding of magnon losses at millikelvin temperatures, which is essential for the future detection of individual propagating magnons.