Amorphous CoFeB films grown on GaAs(001) substrates demonstrating significant in-plane uniaxial magnetic anisotropy were investigated by vector network analyzer ferromagnetic resonance. Distinct in-plane anisotropy of magnetic damping, with a largest maximum-minimum damping ratio of about 109%, was observed via analyzing the frequency dependence of linewidth in a linear manner. As the CoFeB film thickness increases from 3.5 nm to 30 nm, the amorphous structure for all the CoFeB films is maintained while the magnetic damping anisotropy decreases significantly. In order to reveal the inherent mechanism responsible for the anisotropic magnetic damping, studies on time-resolved magneto-optical Kerr effect and high resolution transmission electron microscopy were performed. Those results indicate that the in-plane angular dependent anisotropic damping mainly originates from two-magnon scattering, while the Gilbert damping keeps almost unchanged.

中文翻译：

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GaAs(001) 上非晶 CoFeB 薄膜中磁阻尼的大各向异性

通过矢量网络分析仪铁磁共振研究了在 GaAs(001) 衬底上生长的非晶 CoFeB 薄膜，显示出显着的面内单轴磁各向异性。通过以线性方式分析线宽的频率依赖性，观察到明显的磁阻尼面内各向异性，最大最大最小阻尼比约为 109%。随着 CoFeB 薄膜厚度从 3.5 nm 增加到 30 nm，所有 CoFeB 薄膜的非晶结构保持不变，而磁阻尼各向异性显着降低。为了揭示各向异性磁阻尼的内在机制，进行了时间分辨磁光克尔效应和高分辨率透射电子显微镜研究。