The discovery of efficient magnetization switching upon device activation by spin Hall effect (SHE)-induced spin–orbit torque (SOT) changed the course of magnetic random-access memory (MRAM) research and development. However, for electronic systems with perpendicular magnetic anisotropy (PMA), the use of SOT is still hampered by the necessity of a longitudinal magnetic field to break magnetic symmetry and achieve deterministic switching. In this work, we demonstrate that robust and tunable field-free current-driven SOT switching of perpendicular magnetization can be controlled by the growth protocol in Pt-based magnetic heterostructures. We further elucidate that such growth-dependent symmetry breaking originates from the laterally tilted magnetic anisotropy of the ferromagnetic layer with PMA, a phenomenon that has been largely neglected in previous studies. We show experimentally and in simulation that in a PMA system with tilted anisotropy, the deterministic field-free switching exhibits a conventional SHE-induced damping-like torque feature, and the resulting current-induced effective field shows a nonlinear dependence on the applied current density. This relationship could be potentially misattributed to an unconventional SOT origin.

通过自旋霍尔效应 (SHE) 诱导的自旋轨道扭矩 (SOT) 激活器件时有效磁化切换的发现改变了磁性随机存取存储器 (MRAM) 的研究和开发进程。然而，对于具有垂直磁各向异性 (PMA) 的电子系统，SOT 的使用仍然受到纵向磁场打破磁对称性并实现确定性切换的必要性的阻碍。在这项工作中，我们证明了可以通过 Pt 基磁性异质结构中的生长协议来控制垂直磁化强度的鲁棒且可调的无场电流驱动 SOT 切换。我们进一步阐明，这种依赖于生长的对称性破缺源于具有 PMA 的铁磁层的横向倾斜磁各向异性，这种现象在以前的研究中很大程度上被忽略了。我们通过实验和仿真证明，在具有倾斜各向异性的 PMA 系统中，确定性无场切换表现出传统的 SHE 感应阻尼式扭矩特征，并且由此产生的电流感应有效场显示出对所施加电流密度的非线性依赖性。这种关系可能会被错误地归因于非常规的 SOT 起源。