Field-free switching of perpendicular magnetization through spin-orbit torque in antiferromagnet/ferromagnet/oxide structures
Field-free switching of perpendicular magnetization through spin-orbit torque in antiferromagnet/ferromagnet/oxide structures
复制标题
通过反铁磁体/铁磁体/氧化物结构中的自旋轨道力矩实现垂直磁化的无场切换
DOI：
10.1038/nnano.2016.109
复制
发表时间：
2016-10-01
影响因子：
38.3
通讯作者：
Park, Byong-Guk
中科院分区：
文献类型：
--
作者：
Oh, Young-Wan;Baek, Seung-Heon Chris;Park, Byong-Guk
非磁性重金属的自旋 - 轨道耦合产生的自旋 - 轨道力矩允许垂直磁化的电切换。然而，在横向均匀结构中，这种切换并非纯粹的电切换。实际上需要一个额外的面内磁场来实现确定性切换，这对器件应用是不利的。另一方面，如果反铁磁体能够产生自旋 - 轨道力矩，它们可能实现全电确定性切换，因为所需的磁场可以用它们的交换偏置来替代。在这里我们报道了在IrMn/CoFeB/MgO结构中相当大的自旋 - 轨道力矩。反铁磁的IrMn层还提供一个面内交换偏置场，这使得垂直磁化能够在没有任何外部磁场辅助的情况下实现全电确定性切换。这些特性与相当大的自旋 - 轨道力矩一起，使反铁磁体成为未来自旋电子器件的一个有前途的候选者。我们还表明，各种基于IrMn的结构中自旋 - 轨道力矩的符号无法用现有理论解释，因此需要重大的理论进展。
Spin-orbit torques arising from the spin-orbit coupling of non-magnetic heavy metals allow electrical switching of perpendicular magnetization. However, the switching is not purely electrical in laterally homogeneous structures. An extra in-plane magnetic field is indeed required to achieve deterministic switching, and this is detrimental for device applications. On the other hand, if antiferromagnets can generate spin-orbit torques, they may enable all-electrical deterministic switching because the desired magnetic field may be replaced by their exchange bias. Here we report sizeable spin-orbit torques in IrMn/CoFeB/MgO structures. The antiferromagnetic IrMn layer also supplies an in-plane exchange bias field, which enables all-electrical deterministic switching of perpendicular magnetization without any assistance from an external magnetic field. Together with sizeable spin-orbit torques, these features make antiferromagnets a promising candidate for future spintronic devices. We also show that the signs of the spin-orbit torques in various IrMn-based structures cannot be explained by existing theories and thus significant theoretical progress is required.