论文标题
GHz频率的超低阻尼赤铁矿（$α\ text {-fe} _2 \ text {o} _3 $）的自旋波分散体
Spin wave dispersion of ultra-low damping hematite ($α\text{-Fe}_2\text{O}_3$) at GHz frequencies
论文作者
论文摘要
旋转波（SWS）或镁元素的低磁阻尼和高组速度是功能性镁质设备的两个关键参数。 GHz频率以人工铁磁性石榴石y $ _3 $ _3 $ _5 $ _5 $ o $ o $ $ _ {12} $（YIG）到目前为止，对GHz频率的信号处理和基于波浪的计算的镁化研究。我们报告了对天然矿物质赤铁矿进行的自旋光谱研究（$α\ text {-fe} _2 \ text {o} _3 $），这是一个倾斜的抗fiferromagnet。通过宽带GHz光谱和非弹性光散射，我们在室温下分别确定了$ 1.1 \ times10^{ - 5} $和镁基组速度的阻尼系数。覆盖大约$ k \ 24〜 {\ rm rad}/μ$ m的大量波向量状态，我们发现交换刚度长度相对较短，仅约1Å。在30 mt的小磁场中，SWS的衰减长度估计为1.1 cm，类似于最佳YIG。尽管如此，非弹性光散射仍然令人惊讶地宽，部分不对称的共振峰。它们的特征形状是由较大的组速度，低阻尼和激光束内入射角的分布引起的。我们的结果将赤铁矿作为基于稳定的天然矿物质的快速速度和低损失的宏伟设备的替代和可持续性基础。
Low magnetic damping and high group velocity of spin waves (SWs) or magnons are two crucial parameters for functional magnonic devices. Magnonics research on signal processing and wave-based computation at GHz frequencies focussed on the artificial ferrimagnetic garnet Y$_3$Fe$_5$O$_{12}$ (YIG) so far. We report on spin-wave spectroscopy studies performed on the natural mineral hematite ($α\text{-Fe}_2\text{O}_3$) which is a canted antiferromagnet. By means of broadband GHz spectroscopy and inelastic light scattering, we determine a damping coefficient of $1.1\times10^{-5}$ and magnon group velocities of a few 10 km/s, respectively, at room temperature. Covering a large regime of wave vectors up to $k\approx 24~{\rm rad}/μ$m, we find the exchange stiffness length to be relatively short and only about 1 Å. In a small magnetic field of 30 mT, the decay length of SWs is estimated to be 1.1 cm similar to the best YIG. Still, inelastic light scattering provides surprisingly broad and partly asymmetric resonance peaks. Their characteristic shape is induced by the large group velocities, low damping and distribution of incident angles inside the laser beam. Our results promote hematite as an alternative and sustainable basis for magnonic devices with fast speeds and low losses based on a stable natural mineral.
