标题： YSGAG：量子磁振子学中YIG的理想基底 显示英文标题

标题： YSGAG: The Ideal Substrate for YIG in Quantum Magnonics

摘要： 量子磁子学利用磁子的量子力学特性，以推动纳米尺度的量子信息技术。 铁磁性钇铁石榴石（YIG）因其极长的磁子寿命而闻名，是磁子学的核心材料，通常由于与钆镓石榴石（GGG）衬底具有近完美的晶格匹配而生长为薄膜。 然而，GGG的顺磁性质在低温下会引入对量子应用有害的阻尼机制。 在此，我们研究了在500$\,\mu$m厚的钪镓铝钇石榴石（YSGAG）衬底上生长的150$\,$nm厚的YIG薄膜中的磁阻尼，这是一种新开发的GGG顺磁替代品。 使用最低温度为30$\,$mK的铁磁共振（FMR）光谱学，我们将YIG/YSGAG系统的阻尼特性与传统YIG/GGG参考系统的阻尼特性进行比较。 我们的结果表明，YIG/YSGAG系统从室温到30$\,$mK保持低磁阻尼，其中$\alpha = 4.29\times10^{-5}$是迄今为止报道的YIG/GGG薄膜中最低的值，并且与最好的YIG体材料相当，且没有显著的温度依赖性阻尼增加。 在这种衬底中，与顺磁自旋相关的低温阻尼机制，在GGG中很显著，但被有效消除。 因此，YSGAG作为YIG薄膜在量子磁子学中的理想衬底，正在为基于自旋波的量子技术的发展铺平道路。 显示英文摘要

摘要： Quantum magnonics leverages the quantum mechanical properties of magnons for advancing nanoscale quantum information technologies. Ferrimagnetic yttrium iron garnet (YIG), known for its exceptionally long magnon lifetimes, is a cornerstone material for magnonics and is typically grown into thin films on gadolinium gallium garnet (GGG) substrates due to near-perfect lattice matching. However, the paramagnetic nature of GGG introduces damping mechanisms detrimental to quantum applications at low temperatures. Here, we present a study of magnetic damping in a 150$\,$nm-thick YIG film grown on a 500$\,\mu$m-thick yttrium scandium gallium aluminium garnet (YSGAG) substrate, a newly developed diamagnetic alternative to GGG. Using ferromagnetic resonance (FMR) spectroscopy at temperatures as low as 30$\,$mK, we compare the damping characteristics of the YIG/YSGAG system with those of a conventional YIG/GGG reference system. Our results demonstrate that the YIG/YSGAG system maintains low magnetic damping from room temperature, with $\alpha = 4.29\times10^{-5}$, which is the lowest value reported so far for YIG/GGG films and comparable to the best YIG bulk material, and down to 30$\,$mK, with no significant temperature-dependent increase in damping. In this substrate, the low-temperature damping mechanisms associated with paramagnetic spins, prominent in GGG, are effectively eliminated. Consequently, YSGAG serves as an ideal substrate for YIG films in quantum magnonics and is paving the way for the development of spin-wave-based quantum technologies.