Effects of Oxidation of Top and Bottom Interfaces on the Electric, Magnetic, and Spin-Orbit Torque Properties of Pt/Co/AlOx Trilayers
Effects of Oxidation of Top and Bottom Interfaces on the Electric, Magnetic, and Spin-Orbit Torque Properties of Pt/Co/AlOx Trilayers
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DOI：
10.1103/physrevapplied.13.044029
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发表时间：
2020-04-10
影响因子：
4.6
通讯作者：
Gambardella, Pietro
中科院分区：
文献类型：
--
作者：
Feng, Junxiao;Grimaldi, Eva;Gambardella, Pietro
氧化强烈地影响自旋电子器件中使用的磁性层的性质。我们研究了氧化对Pt/Co/AlOx，Pt/CoOx/Co/AlOx和PtOx/Co/AlOx层的结构，磁性和电学性质以及电流诱导的自旋轨道扭矩（SOTs）的影响。我们展示了如何饱和磁化强度，垂直磁各向异性，异常霍尔电阻，和SOT系统的Pt/Co和Co/Al界面的氧化程度的影响。氧化的Co/Al界面的结果在21%和42%的变化的dampinglike和fieldlike的SOT效率，峰值分别为0.14和0.07。插入的顺磁性CoOx层之间的Pt和Co保持一个非常强的垂直磁各向异性，并提高了dampinglike和fieldlike SOT效率，分别高达0.26和0.20。与最近的报道相比，我们没有发现Pt的氧化导致扭矩的显着增强。相反，我们发现，氧从Pt迁移到Co和Al层，导致随时间变化的氧化曲线和有效的自旋霍尔电导率随氧浓度的增加而降低。最后，我们研究了不同氧化程度的Pt/Co/AlOx中的电流感生开关，发现临界开关电流与Al氧化控制的有效磁各向异性之间存在线性关系。这些结果突出了界面和氧化效应对重金属/铁磁体/氧化物三层，并提供有关如何提高SOT效率和这些系统的磁化开关特性的信息。
Oxidation strongly influences the properties of magnetic layers employed in spintronic devices. We study the effect of oxidation on the structural, magnetic, and electrical properties as well as current-induced spin-orbit torques (SOTs) in Pt/Co/AlOx, Pt/CoOx/Co/AlOx, and PtOx/Co/AlOx layers. We show how the saturation magnetization, perpendicular magnetic anisotropy, anomalous Hall resistance, and SOT are systematically affected by the degree of oxidation of both the Pt/Co and Co/Al interfaces. Oxidation of the Co/Al interface results in a 21% and 42% variation of the dampinglike and fieldlike SOT efficiencies, which peak at 0.14 and 0.07, respectively. The insertion of a paramagnetic CoOx layer between Pt and Co maintains a very strong perpendicular magnetic anisotropy and improves the dampinglike and fieldlike SOT efficiencies, up to 0.26 and 0.20, respectively. In contrast with recent reports, we do not find that the oxidation of Pt leads to a significant enhancement of the torques. Rather, we find that oxygen migrates from Pt to the Co and Al layers, leading to a time-dependent oxidation profile and an effective spin Hall conductivity that decreases with increasing oxygen concentration. Finally, we study current-induced switching in Pt/Co/AlOx with different degrees of oxidation and find a linear relationship between the critical switching current and the effective magnetic anisotropy controlled by the oxidation of Al. These results highlight the importance of interfaces and oxidation effects on the SOT and magnetotransport properties of heavy metal/ferromagnet/oxide trilayers and provide information on how to improve the SOT efficiency and magnetization-switching characteristics of these systems.