We study the impact of irradiation on magnetic tunnel junction (MTJ) films with perpendicular magnetic anisotropy (PMA) and spin–orbit torque (SOT) switching using magneto-optical Kerr effect and transmission electron microscopy. Our results show that the thin-film stack is robust to gamma ionizing dose up to 1 Mrad(Si) and Ta ¹⁺ ion irradiation fluences up to 10 ¹² ions/cm ² , showing SOT PMA MTJs are radiation-hard. But, at very high Ta ¹⁺ ion irradiation between 10 ¹² and 10 ¹⁴ ions/cm ² , reduced coercivity and eventually greatly reduced PMA are observed, corresponding with an increase in intermixing of the CoFeB–MgO layers, particularly at the lower CoFeB–MgO interface. These results agree with displacement damage modeling that predicts higher damage in the layers closer to the bottom heavy metal and substrate. Compared to spin transfer torque and in-plane anisotropy MTJs, needing a top-pinned stack, a thicker heavy metal layer, and perpendicular anisotropy that is pinned out of plane by interfaces, all could make SOT PMA MTJs more susceptible to damage at high doses.

中文翻译：

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辐射对垂直各向异性自旋-轨道转矩磁隧道结的影响

我们使用磁光克尔效应和透射电子显微镜研究了辐射对具有垂直磁各向异性（PMA）和自旋轨道转矩（SOT）转换的磁隧道结（MTJ）膜的影响。我们的结果表明，薄膜堆叠对于高达1 Mrad（Si）的伽马电离剂量和高达10 ¹² ions / cm ^2的Ta ¹⁺离子辐照通量 具有鲁棒性 ，表明SOT PMA MTJ具有抗辐射性。但是，在非常高的Ta ¹⁺离子辐射下，在10 ¹²到10 ¹⁴离子/ cm ^2之间 ，观察到矫顽力降低，最终PMA大大降低，这与CoFeB-MgO层的混合增加有关，尤其是在较低的CoFeB-MgO界面处。这些结果与位移损伤模型相吻合，该模型预测了更靠近底部重金属和基材的层中的更高损伤。与自旋传递扭矩和平面内各向异性MTJ相比，需要顶部固定堆栈，较厚的重金属层以及通过界面固定在平面外的垂直各向异性，所有这些都可能使SOT PMA MTJ在高剂量下更容易受到损坏。