Coherent ac spin current transmission across an antiferromagnetic CoO insulator
Coherent ac spin current transmission across an antiferromagnetic CoO insulator
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DOI：
10.1038/s41467-019-13280-5
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发表时间：
2019-06
影响因子：
16.6
通讯作者：
Qitong Li;Mengmeng Yang;C. Klewe;P. Shafer;A. N’Diaye;D. Hou;Tina Wang;N. Gao;E. Saitoh
中科院分区：
文献类型：
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作者：
Qitong Li;Mengmeng Yang;C. Klewe;P. Shafer;A. N’Diaye;D. Hou;Tina Wang;N. Gao;E. Saitoh
最近发现的自旋电流通过反铁磁绝缘材料传输，为基础物理学和自旋电子学的应用开辟了巨大的机会。目前围绕这个话题的问题是：太赫兹反铁磁磁子是否以及如何介导GHz自旋电流？对于相干交流自旋电流来说，这种频率的不匹配变得尤为关键，这就提出了一个基本问题：GHz的交流自旋电流能否在反铁磁绝缘体内保持其相干性，从而相干地驱动另一个铁磁层的自旋进动？利用元素和时间分辨x射线泵浦探针对Py/Ag/CoO/Ag/Fe75Co25/MgO（001）异质结构的测量，我们证明了Py铁磁共振泵浦的相干GHz交流自旋电流可以在反铁磁CoO绝缘层上相干传输，从而驱动Fe75Co25层的相干自旋进动。进一步的测量结果支持热磁振子而不是倏逝的自旋波作为CoO中相干交流自旋电流的介质。
The recent discovery of spin current transmission through antiferromagnetic insulating materials opens up vast opportunities for fundamental physics and spintronics applications. The question currently surrounding this topic is: whether and how could THz antiferromagnetic magnons mediate a GHz spin current? This mismatch of frequencies becomes particularly critical for the case of coherent ac spin current, raising the fundamental question of whether a GHz ac spin current can ever keep its coherence inside an antiferromagnetic insulator and so drive the spin precession of another ferromagnet layer coherently? Utilizing element- and time-resolved x-ray pump-probe measurements on Py/Ag/CoO/Ag/Fe75Co25/MgO(001) heterostructures, here we demonstrate that a coherent GHz ac spin current pumped by the Py ferromagnetic resonance can transmit coherently across an antiferromagnetic CoO insulating layer to drive a coherent spin precession of the Fe75Co25layer. Further measurement results favor thermal magnons rather than evanescent spin waves as the mediator of the coherent ac spin current in CoO.