标题： 快速长波长交换自旋波在部分补偿的Ga:YIG中 显示英文标题

标题： Fast long-wavelength exchange spin waves in partially-compensated Ga:YIG

摘要： 自旋波在钇铁石榴石（YIG）纳米结构中的研究从基于新型磁子的数据处理应用的角度引起了越来越多的关注。 对于小型器件所需的短波长，群速度与自旋波交换刚度常数 $\lambda_\mathrm{ex}$ 成正比。 使用波矢分辨布里渊光散射 (BLS) 光谱学，我们直接测量了镓取代的 YIG 薄膜中的 $\lambda_\mathrm{ex}$，并表明其大约是纯 YIG 的三倍。 因此，对于波数$k > 4$rad/$\mu$m，自旋波群速度超过了纯 YIG 中的群速度，并且所有$k > 20$rad/$\mu$m 的速度比达到约 3.4 的恒定值。通过振动样品磁强计 (VSM) 和铁磁共振 (FMR) 光谱揭示，厚度低至 59 nm 的 Ga:YIG 薄膜具有低吉尔伯特阻尼 ($\alpha < 10^{-3}$)，饱和磁化强度降低为$\mu_0 M_\mathrm{S}~\approx~20~$mT，并表现出明显的垂直方向单轴各向异性，约为$\mu_0 H_{\textrm{u1}} \approx 95 $mT，这导致了垂直方向的易磁化轴。因此，Ga:YIG 为纳米尺度系统中所有波长的快速和各向同性自旋波传输提供了途径，而无需考虑偶极效应。 显示英文摘要

摘要： Spin waves in yttrium iron garnet (YIG) nano-structures attract increasing attention from the perspective of novel magnon-based data processing applications. For short wavelengths needed in small-scale devices, the group velocity is directly proportional to the spin-wave exchange stiffness constant $\lambda_\mathrm{ex}$. Using wave vector resolved Brillouin Light Scattering (BLS) spectroscopy, we directly measure $\lambda_\mathrm{ex}$ in Ga-substituted YIG thin films and show that it is about three times larger than for pure YIG. Consequently, the spin-wave group velocity overcomes the one in pure YIG for wavenumbers $k > 4$ rad/$\mu$m, and the ratio between the velocities reaches a constant value of around 3.4 for all $k > 20$ rad/$\mu$m. As revealed by vibrating-sample magnetometry (VSM) and ferromagnetic resonance (FMR) spectroscopy, Ga:YIG films with thicknesses down to 59 nm have a low Gilbert damping ($\alpha < 10^{-3}$), a decreased saturation magnetization $\mu_0 M_\mathrm{S}~\approx~20~$mT and a pronounced out-of-plane uniaxial anisotropy of about $\mu_0 H_{\textrm{u1}} \approx 95 $ mT which leads to an out-of-plane easy axis. Thus, Ga:YIG opens access to fast and isotropic spin-wave transport for all wavelengths in nano-scale systems independently of dipolar effects.