Direct observation and imaging of a spin-wave soliton with p-like symmetry.
Direct observation and imaging of a spin-wave soliton with p-like symmetry.
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DOI：
10.1038/ncomms9889
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发表时间：
2015-11-16
影响因子：
16.6
通讯作者：
Dürr HA
中科院分区：
文献类型：
--
作者：
Bonetti S;Kukreja R;Chen Z;Macià F;Hernàndez JM;Eklund A;Backes D;Frisch J;Katine J;Malm G;Urazhdin S;Kent AD;Stöhr J;Ohldag H;Dürr HA
自旋波是自旋的集体激发态，当被纳米接触产生的电流激发时，可以在纳米尺度上以非线性孤子的形式出现。这些孤子被认为本质上具有圆柱对称（即s形），但目前还没有直接的实验观察来证实这一观点。利用时间分辨率为50 ps、空间分辨率为35 nm的高灵敏度时间分辨磁性x射线显微镜，我们能够创建一个实空间自旋波电影，并观察到具有节点线的局域孤子的出现，即具有p型对称。微磁模拟解释了测量结果，并揭示了孤子的对称性可以由磁场控制。我们的研究结果拓宽了对纳米尺度自旋波动力学的理解，对磁性纳米器件的设计具有指导意义。通过纳米接触向铁磁薄膜注入自旋极化电流，有望产生径向对称的自旋波孤子。在这里，作者使用时间分辨x射线显微镜和微磁模拟来证明在纳米接触区与非均匀磁场相关的p类对称的发生。
Spin waves, the collective excitations of spins, can emerge as nonlinear solitons at the nanoscale when excited by an electrical current from a nanocontact. These solitons are expected to have essentially cylindrical symmetry (that is, s-like), but no direct experimental observation exists to confirm this picture. Using a high-sensitivity time-resolved magnetic X-ray microscopy with 50 ps temporal resolution and 35 nm spatial resolution, we are able to create a real-space spin-wave movie and observe the emergence of a localized soliton with a nodal line, that is, with p-like symmetry. Micromagnetic simulations explain the measurements and reveal that the symmetry of the soliton can be controlled by magnetic fields. Our results broaden the understanding of spin-wave dynamics at the nanoscale, with implications for the design of magnetic nanodevices. Injecting spin-polarized current into a ferromagnetic thin film via a nanocontact is expected to generate a radially-symmetric spin wave soliton. Here, the authors use time-resolved x-ray microscopy and micromagnetic simulations to demonstrate the occurrence of p-like symmetry associated with non-uniform magnetic fields in the nanocontact region.