The Correlation Between Magnetic Dead Layer and Perpendicular Magnetic Anisotropy in MgO/CoFeB/Ta Top Structure
The Correlation Between Magnetic Dead Layer and Perpendicular Magnetic Anisotropy in MgO/CoFeB/Ta Top Structure
复制标题
DOI：
10.1109/tmag.2018.2876371
复制
发表时间：
2019-02
影响因子：
2.1
通讯作者：
Shin-Huang Shen;Der-Sheng Lee;Chih-Wei Cheng;Wei-Jen Chan;G. Chern
中科院分区：
文献类型：
--
作者：
Shin-Huang Shen;Der-Sheng Lee;Chih-Wei Cheng;Wei-Jen Chan;G. Chern
MgO基CoFeB结构是具有强垂直磁各向异性（PMA）的典型层状结构之一。然而，其物理性质主要取决于金属保护层的顺序，并且顶部结构对金属层的厚度特别敏感。本文系统研究了Si（衬底）/MgO/CoFeB（1-1.7 nm）/Ta（1-5 nm）顶层结构中帽层对PMA的影响。界面各向异性常数（$\text{K}_{\mathrm {i}}$）与磁死层（MDL）厚度之间存在负相关关系。当MDL从0.1增加到0.6 nm时，K_{i}从2.2减小到1.4 erg/cm ~ 2，两者都表现出非线性的依赖性，在Ta ~ 1.5 nm处发生突变。这些观察结果表明，PMA和MDL上的帽层效应源于Ta扩散导致的MgO/CoFeB和CoFeB/Ta界面的化学劣化。
MgO-based CoFeB structure is one of the typical layered structures with strong perpendicular magnetic anisotropy (PMA). However, the physical properties depend critically upon the sequence of the metal protection layer, and the top structure is especially sensitive to the thickness of the metal layer. In this paper, the cap layer effect on PMA in top structures of Si(substrate)/MgO/CoFeB (1–1.7 nm)/Ta (1–5 nm) is systematically investigated. An inverse correlation between the interface anisotropy constant ( $\text{K}_{\mathrm {i}}$ ) and the thickness of the magnetic dead layer (MDL) is identified. $\text{K}_{\mathrm {i}}$ decreases from 2.2 to 1.4 erg/cm2 while MDL increases from 0.1 to 0.6 nm, both showing a nonlinear dependence upon the Ta thickness with an abrupt change at Ta ~ 1.5 nm. These observations indicate that the cap layer effect on both PMA and MDL originates from the chemical deterioration at MgO/CoFeB and CoFeB/Ta interfaces by Ta diffusion.