Roles of interface roughness and internal stress in magnetic anisotropy of CoPt/AlN multilayer films
Roles of interface roughness and internal stress in magnetic anisotropy of CoPt/AlN multilayer films
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DOI：
10.1016/j.actamat.2012.08.053
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发表时间：
2012-11
期刊：
影响因子：
9.4
通讯作者：
Youxing Yu;Ji Shi;Yoshio Nakamura
中科院分区：
文献类型：
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作者：
Youxing Yu;Ji Shi;Yoshio Nakamura
通过系统地改变CoPt层的标称厚度tCoPt（1-10nm）和退火温度Ta(300-500°C)，研究了CoPt/AlN多层膜的磁各向异性。沉积膜在tCoPt全范围内表现为面内磁各向异性，而退火膜在tCoPt小范围内表现为垂直磁各向异性，但当tCoPt超过一定厚度时转变为面内磁各向异性。这种各向异性转换的临界厚度随着厚度的增加而增加。本工作得到的最大PMA为1.13×107ergcm−3。采用高分辨率横截面电子显微镜分析了界面粗糙度，采用Debye指数形状的突变界面模型分析了x射线反射率。采用等双轴应力模型，用x射线衍射分析了其内应力。结果表明：当温度升高到500℃时，CoPt/AlN界面粗糙度从0.385nm减小到0.158nm，内应力从- 2.36GPa（压缩）增加到1.73GPa（拉伸）；研究了界面粗糙度和内应力对CoPt/AlN多层膜磁各向异性的影响。
Magnetic anisotropy of CoPt/AlN multilayer films has been studied by systematically varying the nominal thickness of CoPt layers, tCoPt(1–10nm), and the annealing temperature, Ta(300–500°C). The as-deposited films show in-plane magnetic anisotropy in the full range of tCoPt, whereas the annealed films show perpendicular magnetic anisotropy (PMA) within small tCoPtbut change to in-plane magnetic anisotropy when tCoPtis over a certain thickness. The critical thickness for such anisotropic transformations increases as the Taincreases. The maximum PMA obtained in this work is 1.13×107ergcm−3. The interface roughness was analyzed by cross-sectional high-resolution electron microscopy and X-ray reflectivity using an abrupt interface model with a Debye exponent shape. The internal stress was analyzed by X-ray diffraction using an equal biaxial stress model. The results show that the CoPt/AlN interface roughness decreases from 0.385nm to 0.158nm and the internal stress increases from −2.36GPa (compressive) to 1.73GPa (tensile), as the Taincreases to 500°C. The roles of the interface roughness and the internal stress in the magnetic anisotropy of CoPt/AlN multilayer films are studied.