Large enhancement of magnetic damping in the presence of domain walls in spin valves
Large enhancement of magnetic damping in the presence of domain walls in spin valves
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DOI：
10.1088/1361-6463/abdce6
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发表时间：
2021-04
期刊：
影响因子：
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通讯作者：
Jian Su;Wei He;Gang Li;H. Bai;Zi-Zhong Zhu;Ying Zhang;Z. Cheng;J. Cai
中科院分区：
文献类型：
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作者：
Jian Su;Wei He;Gang Li;H. Bai;Zi-Zhong Zhu;Ying Zhang;Z. Cheng;J. Cai
具有大交换偏置的自旋阀 IrMn/CoFe/Cu/CoFeB 中 CoFeB 自由层的磁阻尼通过一系列固定磁场下的扫频铁磁共振来表征。阻尼常数在平行和反平行磁化配置之间显示出很小的差异，与理论预测一致。值得注意的是，在反转下钉扎 CoFe 层的中间状态下，CoFeB 层的有效阻尼常数从 0.0119 显着提高到 0.0292。这种增强明显超过了泵浦自旋流的影响，主要是由于当其磁化部分反转时，被钉扎 CoFe 层的磁畴壁 (DW) 中出现的杂散场引起的不均匀展宽和/或双磁振子散射。同时，在 DW 存在的情况下也观察到共振频率偏移。我们的结果证实了钉扎层 DW 对自旋阀磁阻尼的强烈影响，在处理异质结构中非局域自旋输运引起的阻尼时应适当排除这种影响。
Magnetic damping of the free layer of CoFeB in the spin valve IrMn/CoFe/Cu/CoFeB with large exchange bias has been characterized by frequency-swept ferromagnetic resonance under a series of fixed magnetic fields. The damping constant shows little difference between the parallel and antiparallel magnetization configurations, consistent with the theoretical prediction. Remarkably, in the intermediate states of the pinned CoFe layer under reversal, the effective damping constant of the CoFeB layer is significantly enhanced from 0.0119 up to 0.0292. This enhancement, exceeding the effect of the pumped spin current appreciably, is mainly due to the inhomogeneous broadening and/or two-magnon scattering caused by the stray field emerging from the domain walls (DW) of the pinned CoFe layer when its magnetization is partially reversed. Meanwhile, a resonance frequency shift is also observed in the presence of DW. Our result confirms the strong influence of the pinned layer DW on the magnetic damping in spin valves, which should be properly excluded while dealing with the nonlocal spin-transport-induced damping in heterostructures.