Ultrafast domain wall motion in ferrimagnets induced by magnetic anisotropy gradient
Ultrafast domain wall motion in ferrimagnets induced by magnetic anisotropy gradient
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DOI：
10.1103/physrevb.101.024414
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发表时间：
2019-10
影响因子：
3.7
通讯作者：
W. H. Li;Z. Jin;D. L. Wen;X. Zhang;M. Qin;J. Liu
中科院分区：
文献类型：
--
作者：
W. H. Li;Z. Jin;D. L. Wen;X. Zhang;M. Qin;J. Liu
补偿铁磁体中的超快磁动力学不仅与反铁磁动力学相似，更重要的是，为未来的自旋电子器件开辟了新的机会[Kim et al., Nat. Mater. 16, 1187(2017)]。寻找低功耗、高效率的控制域壁的方法是器件设计的关键问题之一。在这项工作中，我们提出使用电压控制磁各向异性梯度作为激励源来驱动铁磁体中的畴壁运动。基于集体坐标理论对各向异性梯度下的超快壁运动进行了理论预测，并得到了原子微磁模拟的证实。在角动量补偿点处实现了反铁磁自旋动力学，在小梯度下，壁面移动速度恒定，在大梯度下，壁面宽度变宽，壁面移动速度略有加快。对于非零净角动量，Walker击穿发生在临界各向异性梯度处，该梯度被第二各向异性和界面Dzyaloshinskii-Moriya相互作用显著增强，这对进一步的实验（包括材料选择和器件几何设计）具有重要意义。更重要的是，这项工作揭示了一种低功耗和高效的方法来控制铁磁体中的畴壁，有利于未来的自旋电子应用。
The ultrafast magnetic dynamics in compensated ferrimagnets not only is similar to antiferromagnetic dynamics but, more importantly, opens new opportunities for future spintronic devices [Kim et al., Nat. Mater. 16, 1187 (2017)]. One of the most essential issues for device design is searching for low-power-consuming and high-efficient methods of controlling the domain wall. In this work, we propose to use the voltage-controlled magnetic anisotropy gradient as an excitation source to drive the domain wall motion in ferrimagnets. The ultrafast wall motion under the anisotropy gradient is predicted theoretically based on the collective coordinate theory, which is also confirmed by the atomistic micromagnetic simulations. The antiferromagnetic spin dynamics is realized at the angular momentum compensation point, and the wall shifting has a constant speed under small gradients and can be slightly accelerated under large gradients due to the broadened wall width during the motion. For nonzero net angular momentum, the Walker breakdown occurs at a critical anisotropy gradient significantly enhanced by the second anisotropy and interfacial Dzyaloshinskii-Moriya interaction, which is highly appreciated for further experiments, including the materials selection and device geometry design. More importantly, this work unveils a low-power-consuming and highly efficient method of controlling the domain wall in ferrimagnets, benefiting future spintronic applications.