Spin dynamics in ferromagnets : Gilbert damping and two-magnon scattering
Spin dynamics in ferromagnets : Gilbert damping and two-magnon scattering
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DOI：
10.1103/physrevb.76.104416
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发表时间：
2007-09
影响因子：
3.7
通讯作者：
K. Zakeri;J. Lindner;I. Barsukov;R. Meckenstock;M. Farle;U. V. Hörsten;H. Wende;W. Keune;J. Roc
中科院分区：
文献类型：
--
作者：
K. Zakeri;J. Lindner;I. Barsukov;R. Meckenstock;M. Farle;U. V. Hörsten;H. Wende;W. Keune;J. Roc
以外延${\mathrm{Fe}}_{3}\mathrm{Si}$薄膜为原型系统，利用1和$70\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$之间的铁磁共振（FMR）研究了自旋系统动态激发后的磁弛豫过程。通过频率和角度相关的FMR同时识别出耗散的、各向同性的吉尔伯特阻尼$G$和各向异性的双磁振子散射$\ensuremath{\Gamma}$两个弛豫通道，并进行了定量分析。在⟨100⟩和⟨110⟩方向上传播的自旋波的晶体缺陷上由于双磁振子散射的散射率，$\ensuremath{\gamma}{\ensuremath{\Gamma}}_{⟨100⟩}=0.25(2)\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$和$\ensuremath{\gamma}{\ensuremath{\Gamma}}_{⟨110⟩}=0.04(2)\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$，以及Gilbert阻尼项$G=0.051(1)\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$被确定。我们发现从$8\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}40\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$开始改变薄膜厚度和稍微改变铁浓度会影响弛豫通道。我们的研究结果揭示了纵向和横向弛豫过程的贡献，这可能对理解磁性结构中的自旋波动力学具有普遍的重要性。
The magnetic relaxation processes following the dynamical excitation of the spin system of ferromagnets are investigated by ferromagnetic resonance (FMR) between 1 and $70\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$ using epitaxial ${\mathrm{Fe}}_{3}\mathrm{Si}$ films as a prototype system. Two relaxation channels, i.e., dissipative, isotropic Gilbert damping $G$ as well as anisotropic two-magnon scattering $\ensuremath{\Gamma}$, are simultaneously identified by frequency and angle dependent FMR and quantitatively analyzed. The scattering rates due to two-magnon scattering at crystallographic defects for spin waves propagating in ⟨100⟩ and ⟨110⟩ directions, $\ensuremath{\gamma}{\ensuremath{\Gamma}}_{⟨100⟩}=0.25(2)\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$ and $\ensuremath{\gamma}{\ensuremath{\Gamma}}_{⟨110⟩}=0.04(2)\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$, and the Gilbert damping term $G=0.051(1)\phantom{\rule{0.3em}{0ex}}\mathrm{GHz}$ are determined. We show that changing the film thickness from $8\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}40\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ and slightly modifying the Fe concentration influence the relaxation channels. Our results, which reveal the contributions of longitudinal and transverse relaxation processes may be of general importance for the understanding of spin-wave dynamics in magnetic structures.