Observation and formation mechanism of 360° domain wall rings in synthetic anti-ferromagnets with interlayer chiral interactions
Observation and formation mechanism of 360° domain wall rings in synthetic anti-ferromagnets with interlayer chiral interactions
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DOI：
10.1063/5.0158119
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发表时间：
2023-05
影响因子：
4
通讯作者：
Miguel A. Cascales Sandoval;A. Hierro-Rodr'iguez;S. Ruiz-G'omez;L. Skoric;C. Donnelly;M. A. Niño;E. Vedmedenko;D. McGrouther;S. McVitie;S. Flewett;N. Jaouen;M. Foerster;A. Fern'andez-Pacheco
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作者：
Miguel A. Cascales Sandoval;A. Hierro-Rodr'iguez;S. Ruiz-G'omez;L. Skoric;C. Donnelly;M. A. Niño;E. Vedmedenko;D. McGrouther;S. McVitie;S. Flewett;N. Jaouen;M. Foerster;A. Fern'andez-Pacheco
层间Dzyaloshinskii-Moriya相互作用(IL-DMI)手征耦合多层异质结构中不同铁磁层中的自旋。到目前为止，含有IL-DMI的样品已经利用磁测量和磁传输技术进行了研究，其中相互作用表现为可调的手性交换偏置场。在这里，我们研究了含有IL-DMI的合成反铁磁体(SAF)在施加退磁序列后磁化矢量的纳米级构型。我们将不同的全局磁场偏移量添加到退磁序列中，以研究当IL-DMI交换偏置场被完全或部分补偿时形成的状态。对于剩余磁态的磁成像和矢量重建，我们利用X射线磁性圆二色光电子显微镜，证明形成了直径通常为0.53.0μm的360°磁化壁环。只有当由IL-DMI引起的交换偏置场没有被磁场偏移量完全补偿时，才能观察到这些自旋织构。通过微磁模拟、磁荷分布和拓扑学论证的结合，我们得出结论：要观察这些环，需要一个分量平行和垂直于SAF各向异性轴的非零剩余有效场。这项工作展示了由IL-DMI引起的交换偏置场如何在反转过程中导致复杂的亚稳自旋态，这对未来自旋电子器件的发展具有重要意义。
The interlayer Dzyaloshinskii–Moriya interaction (IL-DMI) chirally couples spins in different ferromagnetic layers of multilayer heterostructures. So far, samples with IL-DMI have been investigated utilizing magnetometry and magnetotransport techniques, where the interaction manifests as a tunable chiral exchange bias field. Here, we investigate the nanoscale configuration of the magnetization vector in a synthetic anti-ferromagnet (SAF) with IL-DMI, after applying demagnetizing field sequences. We add different global magnetic field offsets to the demagnetizing sequence in order to investigate the states that form when the IL-DMI exchange bias field is fully or partially compensated. For magnetic imaging and vector reconstruction of the remanent magnetic states, we utilize x-ray magnetic circular dichroism photoemission electron microscopy, evidencing the formation of 360° domain wall rings of typically 0.5–3.0 μm in diameter. These spin textures are only observed when the exchange bias field due to the IL-DMI is not perfectly compensated by the magnetic field offset. From a combination of micromagnetic simulations, magnetic charge distribution, and topology arguments, we conclude that a non-zero remanent effective field with components both parallel and perpendicular to the anisotropy axis of the SAF is necessary to observe the rings. This work shows how the exchange bias field due to IL-DMI can lead to complex metastable spin states during reversal, important for the development of future spintronic devices.