Handedness anomaly in a non-collinear antiferromagnet under spin–orbit torque
Handedness anomaly in a non-collinear antiferromagnet under spin–orbit torque
复制标题
DOI：
10.1038/s41563-023-01620-2
复制
发表时间：
2023-08
期刊：
影响因子：
41.2
通讯作者：
Juyoung Yoon;Pengxiang Zhang;C. Chou;Y. Takeuchi;T. Uchimura;J. Hou;Jiahao Han;S. Kanai;Hideo Ohno;S. Fukami;Luqiao Liu
中科院分区：
文献类型：
--
作者：
Juyoung Yoon;Pengxiang Zhang;C. Chou;Y. Takeuchi;T. Uchimura;J. Hou;Jiahao Han;S. Kanai;Hideo Ohno;S. Fukami;Luqiao Liu
非共线反铁磁体是一种新兴的自旋电子材料，因为它们不仅具有反铁磁体的一般优点，而且还可以实现更高级的功能。最近，在一个有趣的非共线反铁磁体Mn3Sn，八极矩被定义为集体磁序参数，自旋轨道转矩（SOT）开关已实现在看似相同的协议，在铁磁体。然而，探索未知的八极矩动力学并将其与铁磁体的磁化矢量进行对比是非常重要的。在这里，我们报告了一个手性异常的SOT驱动的动力学Mn3Sn：当自旋电流注入，八极矩旋转方向相反的个别时刻，导致SOT开关极性不同的铁磁体。通过使用二次谐波和直流磁测量，我们跟踪SOT效应八极矩在其旋转过程中，并揭示了旋向异常源于注入的自旋和Mn3Sn的独特的手征自旋结构之间的相互作用。进一步建立了磁八极矩的转矩平衡方程，量化了SOT效率。我们的发现为理解和实施非共线反铁磁体的电操纵提供了指导，非共线反铁磁体在本质上不同于公认的共线磁体。
Non-collinear antiferromagnets are an emerging family of spintronic materials because they not only possess the general advantages of antiferromagnets but also enable more advanced functionalities. Recently, in an intriguing non-collinear antiferromagnet Mn3Sn, where the octupole moment is defined as the collective magnetic order parameter, spin–orbit torque (SOT) switching has been achieved in seemingly the same protocol as in ferromagnets. Nevertheless, it is fundamentally important to explore the unknown octupole moment dynamics and contrast it with the magnetization vector of ferromagnets. Here we report a handedness anomaly in the SOT-driven dynamics of Mn3Sn: when spin current is injected, the octupole moment rotates in the opposite direction to the individual moments, leading to a SOT switching polarity distinct from ferromagnets. By using second-harmonic and d.c. magnetometry, we track the SOT effect onto the octupole moment during its rotation and reveal that the handedness anomaly stems from the interactions between the injected spin and the unique chiral-spin structure of Mn3Sn. We further establish the torque balancing equation of the magnetic octupole moment and quantify the SOT efficiency. Our finding provides a guideline for understanding and implementing the electrical manipulation of non-collinear antiferromagnets, which in nature differs from the well-established collinear magnets.