Department of Materials Science and Engineering, Korea University, Seoul, 02841, Korea.
Sci Rep. 2018 Jan 19;8(1):1266. doi: 10.1038/s41598-018-19656-9.
The perpendicular magnetic anisotropy (PMA) properties of Pt/Co/MgO trilayers are investigated as a function of the MgO sputtering power (P) and its thickness (t), both of which are important parameters affecting the degree of oxygen interpenetration into Co during sputtering. A strong PMA is achieved at small values of P and t, where the oxygen interpenetration into Co is expected to be small. The range of oxygen interpenetration is relatively extended in such a way that it affects both the Pt/Co and Co/MgO interfaces. The PMA properties of as-deposited samples are improved by post-annealing for temperatures up to 400 °C examined in this study, probably due to the diffusion of the interpenetrated oxygen atoms toward the Co/MgO interface. In a structure of Pt/Co (0.6 nm)/MgO (2 nm), which is fabricated at P = 50 W and then annealed at 400 °C, a huge saturation field is achieved (over 40 kOe) indicating a very strong PMA. Between the two interfaces of Pt/Co and Co/MgO, the PMA is mainly due to the former in the as-deposited state, but the contribution of the latter increases with the increase in the annealing temperature.
Pt/Co/MgO 三层膜的垂直各向异性磁性能（PMA）随 MgO 溅射功率（P）和厚度（t）的变化而变化，这两个参数都是影响溅射过程中氧向 Co 中渗透程度的重要因素。在 P 和 t 值较小时，会获得较强的 PMA，此时氧向 Co 中的渗透预计较小。氧的渗透范围相对较大，影响了 Pt/Co 和 Co/MgO 界面。在本研究中，对沉积样品进行高达 400°C 的退火处理，可改善其 PMA 性能，这可能是由于渗透氧原子向 Co/MgO 界面扩散所致。在 Pt/Co（0.6nm）/MgO（2nm）结构中，在 P=50W 下制备并在 400°C 下退火后，实现了巨大的饱和场（超过 40kOe），表明具有很强的 PMA。在 Pt/Co 和 Co/MgO 两个界面之间，PMA 主要归因于沉积态下的前一个界面，但随着退火温度的升高，后一个界面的贡献增加。
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