Synthetic antiferromagnetic (SAF) multilayers offer a highly versatile platform for skyrmionic devices, providing skyrmions with exceptional mobility and a negligible skyrmion Hall effect (SkHE). However, detecting antiferromagnetic skyrmions is challenging due to their antiparallel spin alignment, and their behavior within asymmetrically parametrized ferromagnetic layers remains unclear. Here, we theoretically investigate the stability and transport properties of antiferromagnetically coupled skyrmions in multilayer systems comprising two ferromagnetic layers with distinct interfacial Dzyaloshinskii-Moriya interactions (DMIs). We show that coupled skyrmion pairs of opposite charge are stable over broad parameter ranges, even when the DMI vectors differ in both magnitude and sense. Our investigation into the transport properties reveals that the SkHE cancellation due to the topological neutrality of the skyrmion pair is robust against imbalances in several material parameters, including DMI and Gilbert damping, but is highly sensitive to imbalance in the current densities and saturation magnetizations. This suggests that synthetic ferrimagnets are generally ineffective in eliminating the SkHE. In contrast, we show that magnetically compensated SAF stacks with antiparallel DMI vectors not only eliminate the SkHE but also facilitate skyrmion detection.

中文翻译：

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非对称多层合成反铁磁斯格明子的稳定性和动力学


合成反铁磁 (SAF) 多层膜为斯格明子器件提供了高度通用的平台，为斯格明子提供了卓越的迁移率和可忽略不计的斯格明子霍尔效应 (SkHE)。然而，由于反铁磁斯格明子的反平行自旋排列，检测它们具有挑战性，并且它们在不对称参数化铁磁层内的行为仍不清楚。在这里，我们从理论上研究了多层系统中反铁磁耦合斯格明子的稳定性和传输特性，该系统包含两个具有不同界面 Dzyaloshinskii-Moriya 相互作用 (DMIs) 的铁磁层。我们证明，即使 DMI 向量的大小和方向不同，带相反电荷的耦合斯格明子对在广泛的参数范围内也是稳定的。我们对输运特性的研究表明，由于斯格明子对的拓扑中性而导致的 SkHE 抵消对于包括 DMI 和吉尔伯特阻尼在内的多个材料参数的不平衡具有鲁棒性，但对电流密度和饱和磁化强度的不平衡高度敏感。这表明合成亚铁磁体通常无法有效消除 SkHE。相比之下，我们表明具有反平行 DMI 矢量的磁补偿 SAF 堆栈不仅消除了 SkHE，而且还促进了斯格明子检测。