Spin-orbit torque (SOT) induced magnetisation switching in CoFeB/Ta/CoFeB trilayer with two CoFeB layers exhibiting in-plane magnetic anisotropy (IPMA) and perpendicular magnetic anisotropy (PMA) is investigated. Interlayer exchange coupling (IEC), measured using ferromagnetic resonance technique is modified by varying thickness of Ta spacer. The evolution of the IEC leads to different orientation of the magnetic anisotropy axes of two CoFeB layers: for thicker Ta layer where magnetisation prefers antiferromagnetic ordering and for thinner Ta layer where ferromagnetic coupling exists. Magnetisation state of the CoFeB layer exhibiting PMA is controlled by the spin-polarized current originating from SOT in μm sized Hall bars. The evolution of the critical SOT current density with Ta thickness is presented, showing an increase with decreasing tTa, which coincides with the coercive field dependence. In a narrow range of tTa corresponding to the ferromagnetic IEC, the field-free SOT-induced switching is achieved.
@article{arxiv.2006.12068,
title = {Spin-orbit torque induced magnetisation dynamics and switching in CoFeB/Ta/CoFeB system with mixed magnetic anisotropy},
author = {Stanisław Łazarski and Witold Skowroński and Krzysztof Grochot and Wiesław Powroźnik and Jarosław Kanak and Marek Schmidt and Tomasz Stobiecki},
journal= {arXiv preprint arXiv:2006.12068},
year = {2021}
}