Spin-orbit torques in locally and globally noncentrosymmetric crystals: Antiferromagnets and ferromagnets
Spin-orbit torques in locally and globally noncentrosymmetric crystals: Antiferromagnets and ferromagnets
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DOI：
10.1103/physrevb.95.014403
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发表时间：
2017-01-05
影响因子：
3.7
通讯作者：
Jungwirth, T.
中科院分区：
文献类型：
--
作者：
Zelezny, J.;Gao, H.;Jungwirth, T.
阻碍反铁磁体实际应用的主要障碍之一是难以操纵磁序参量。最近，根据理论预测[J]。Zelezny等人，物理修订信函113，157201（2014）]，证明了反铁磁体中磁矩的电切换[P.瓦德利et al.，Science 351，587（2016）]。这种转变是由于所谓的自旋轨道力矩，这在铁磁体中已经得到了广泛的研究。在这种现象中，电流引起了与有序局域矩耦合的非平衡自旋极化交换，从而对有序参数施加了力矩。在这里，我们给出了一个一般的系统分析的自旋轨道力矩的对称性，在本地和全球非中心对称的晶体。我们研究的对称性时，允许一个非零的扭矩，当是有效的扭矩，其依赖于所施加的电流方向和方向的磁矩。为了比较，我们考虑反铁磁和铁磁订单。在两个有代表性的模型晶体中，我们进行微观计算的自旋-轨道扭矩，以说明其对称性，并突出条件下，自旋-轨道扭矩可以有效地操纵反铁磁力矩。
One of the main obstacles that prevents practical applications of antiferromagnets is the difficulty of manipulating the magnetic order parameter. Recently, following the theoretical prediction [J.. Zelezny et al., Phys. Rev. Lett. 113, 157201 (2014)], the electrical switching of magnetic moments in an antiferromagnet was demonstrated [P. Wadley et al., Science 351, 587 (2016)]. The switching is due to the so-called spin-orbit torque, which has been extensively studied in ferromagnets. In this phenomena a nonequilibrium spin-polarization exchange coupled to the ordered local moments is induced by current, hence exerting a torque on the order parameter. Here we give a general systematic analysis of the symmetry of the spin-orbit torque in locally and globally noncentrosymmetric crystals. We study when the symmetry allows for a nonzero torque, when is the torque effective, and its dependence on the applied current direction and orientation of magnetic moments. For comparison, we consider both antiferromagnetic and ferromagnetic orders. In two representative model crystals we perform microscopic calculations of the spin-orbit torque to illustrate its symmetry properties and to highlight conditions under which the spin-orbit torque can be efficient for manipulating antiferromagnetic moments.