The antiferromagnet (AFM) and ferromagnet (FM) interface is a unique branch of magnetics of broad scientific interest. AFMs play an important role in spin-orbit torque devices based on their ability to generate spin-polarized current and exchange bias when combined with FMs. In this study, an interesting spin-orbit torque (SOT) ratchet involving the exchange spring effect in an IrMn/CoFeB bilayer device with perpendicular anisotropy and exchange bias is developed. The combined use of electrical and spectroscopic analysis reveals that the exchange spring in IrMn/CoFeB bilayer yields unidirectional anisotropy, resulting in a collinear/orthogonal AFM/FM spin configuration at the interface upon switching CoFeB magnetization upward/downward. The ratcheting characteristics resulting from unidirectional anisotropy manifest in SOT switching. In this process, magnetization against the exchange spring features digital-like switching with a sharp transition, whereas the reverse function is characteristic of analog switching with a gradual transition tail. The dual digital-analog characteristics of the IrMn/CoFeB bilayer may be of benefit in neuromorphic and memory applications.

中文翻译：

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通过交换弹簧在铁磁体/反铁磁体接口处的自旋轨道扭矩棘轮

反铁磁体 (AFM) 和铁磁体 (FM) 界面是具有广泛科学意义的磁学的一个独特分支。AFM 在与 FM 结合时产生自旋极化电流和交换偏压的能力在自旋轨道扭矩装置中发挥着重要作用。在这项研究中，开发了一种有趣的自旋轨道扭矩 (SOT) 棘轮，该棘轮涉及具有垂直各向异性和交换偏压的 IrMn/CoFeB 双层器件中的交换弹簧效应。电学和光谱分析的结合使用表明，IrMn/CoFeB 双层中的交换弹簧产生单向各向异性，导致在向上/向下切换 CoFeB 磁化强度时界面处的共线/正交 AFM/FM 自旋配​​置。单向各向异性导致的棘轮特性体现在 SOT 切换中。在这个过程中，对交换弹簧的磁化具有具有急剧过渡的类数字开关的特征，而反向功能具有具有渐变尾部的模拟开关的特征。IrMn/CoFeB 双层的双数模特性在神经形态和记忆应用中可能是有益的。