Gilbert damping constants of Ta/CoFeB/MgO(Ta) thin films measured by optical detection of precessional magnetization dynamics
Gilbert damping constants of Ta/CoFeB/MgO(Ta) thin films measured by optical detection of precessional magnetization dynamics
复制标题
DOI：
10.1103/physrevb.89.174416
复制
发表时间：
2014-05-13
影响因子：
3.7
通讯作者：
Miyazaki, Terunobu
中科院分区：
文献类型：
--
作者：
Iihama, Satoshi;Mizukami, Shigemi;Miyazaki, Terunobu
使用全光泵浦探针方法研究了 Ta/CoFeB/MgO 和 Ta/CoFeB/Ta 薄膜的磁化动力学。当考虑薄膜中的磁各向异性分布时，Landau-Lifshitz-Gilbert 方程很好地解释了进动频率和弛豫时间的磁场强度和施加场方向的依赖性。还讨论了两种堆叠膜获得的 a 值的厚度依赖性。 a 值随着 CoFeB 反厚度 (t(CoFeB)) 的增加而线性增加。 Ta/CoFeB/MgO 薄膜的 a 对 1/t(CoFeB) 特性的斜率小于 Ta/CoFeB/Ta 薄膜，这意味着 a 的增强是由 CoFeB/Ta 界面引起的。比较a和垂直磁各向异性常数Ku的退火温度依赖性，发现a和Ku之间没有相关性。
The magnetization dynamics of both Ta/CoFeB/MgO and Ta/CoFeB/Ta films were investigated using an all-optical pump-probe method. The magnetic field strength and the applied field direction dependencies of the precession frequency and the relaxation time were explained well by the Landau-Lifshitz-Gilbert equation when taking the magnetic anisotropy distribution in the film into account. The thickness dependence of the a values obtained for both stacked films was also discussed. The a values increased linearly with increasing inverse CoFeB thickness (t(CoFeB)). The slope of the a vs 1/t(CoFeB) characteristic for Ta/CoFeB/MgO films was smaller than that for Ta/CoFeB/Ta films, implying that the enhancement of a was caused by the CoFeB/Ta interface. Comparison of the annealing temperature dependence of a and the perpendicular magnetic anisotropy constant Ku revealed no correlation between a and Ku.