Spin waves and their quanta, magnons, are promising candidates for next-generation electronic devices, due to their low-power consumption and compatibility with radio-frequency-based electronic devices. For achieving magnon-based hybrid quantum systems for quantum memory and computation, the investigation of spin-wave propagation at cryogenic temperatures is highly required. In this article, we report the excitation and detection of exchange spin waves with wavelengths of tens of nanometers in an yttrium iron garnet (YIG) thin film at cryogenic temperatures. We find that the exchange spin waves are unidirectional in all temperature ranges, owing to the chiral dynamical dipolar coupling between the spin-wave mode in the YIG and the ferromagnetic resonance mode in the cobalt nanowire. Notably, a high exchange spin-wave group velocity of 2 km s⁻¹ at 10 K is observed. Our results are promising for the development of high-speed and energy-efficient quantum magnonic devices operating at cryogenic temperatures.

中文翻译：

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低温下磁绝缘体薄膜中交换自旋波的激发

自旋波及其量子磁振子由于功耗低且与基于射频的电子设备兼容，因此成为下一代电子设备的有希望的候选者。为了实现用于量子存储和计算的基于磁振子的混合量子系统，非常需要研究低温下的自旋波传播。在本文中，我们报告了低温下钇铁石榴石（YIG）薄膜中波长为数十纳米的交换自旋波的激发和检测。我们发现，由于 YIG 中的自旋波模式与钴纳米线中的铁磁共振模式之间的手性动态偶极耦合，交换自旋波在所有温度范围内都是单向的。值得注意的是，在 10 K 时观察到了2 km s ^-1的高交换自旋波群速度。我们的研究结果对于开发在低温下运行的高速、节能的量子磁子器件很有希望。