Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University in Poznań, Uniwersytetu Poznanskiego 2, 61-614, Poznan, Poland.
Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, 351-0198, Japan.
Sci Rep. 2023 May 26;13(1):8532. doi: 10.1038/s41598-023-35739-8.
Magnetic damping controls the performance and operational speed of many spintronics devices. Being a tensor quantity, the damping in magnetic thin films often shows anisotropic behavior with the magnetization orientation. Here, we have studied the anisotropy of damping in Ta/CoFeB/MgO heterostructures, deposited on thermally oxidized Si substrates, as a function of the orientation of magnetization. By performing ferromagnetic resonance (FMR) measurements based on spin pumping and inverse spin Hall effect (ISHE), we extract the damping parameter in those films and find that the anisotropy of damping contains four-fold and two-fold anisotropy terms. We infer that four-fold anisotropy originates from two-magnon scattering (TMS). By studying reference Ta/CoFeB/MgO films, deposited on LiNbO substrates, we find that the two-fold anisotropy is correlated with in-plane magnetic anisotropy (IMA) of the films, suggesting its origin as the anisotropy in bulk spin-orbit coupling (SOC) of CoFeB film. We conclude that when IMA is very small, it's correlation with two-fold anisotropy cannot be experimentally identified. However, as IMA increases, it starts to show a correlation with two-fold anisotropy in damping. These results will be beneficial for designing future spintronics devices.
磁阻尼控制着许多自旋电子设备的性能和工作速度。作为张量量，磁薄膜中的阻尼通常表现出各向异性，与磁化方向有关。在这里，我们研究了在热氧化硅衬底上沉积的 Ta/CoFeB/MgO 异质结构中阻尼的各向异性，作为磁化方向的函数。通过基于自旋泵浦和反自旋霍尔效应（ISHE）的铁磁共振（FMR）测量，我们提取了这些薄膜中的阻尼参数，并发现阻尼的各向异性包含四重各向异性和二重各向异性项。我们推断四重各向异性源于双激子散射（TMS）。通过研究在 LiNbO 衬底上沉积的 Ta/CoFeB/MgO 参考薄膜，我们发现二重各向异性与薄膜的面内磁各向异性（IMA）相关，表明其起源于 CoFeB 薄膜的体各向异性自旋轨道耦合（SOC）。我们得出结论，当 IMA 非常小时，其与二重各向异性的相关性无法在实验中确定。然而，随着 IMA 的增加，它开始表现出与阻尼中二重各向异性的相关性。这些结果将有利于设计未来的自旋电子设备。
Zotero 插件
