CoFeB/AlO_x/Ta及AlO_x/CoFeB/Ta结构中垂直易磁化效应的研究

The research of the perpendicular magnetic anisotropy in CoFeB/AlO_x/Ta and AlO_x/CoFeB/Ta structures

本文详细研究了在不同氧化层和铁磁层厚度情况下,底层CoFeB/AlOx/Ta结构和顶层AlOx/CoFeB/Ta结构中的垂直磁各向异性.在底层CoFeB/AlOx/Ta结构中观察到了垂直磁化的磁滞回线,证明了其垂直易磁化效应的存在;而在顶层AlOx/CoFeB/Ta结构中却没有观察到类似的磁滞回线.对这种对称结构中的非对称现象进行了分析.研究还发现不同的氧化层和铁磁层厚度均会影响层间界面相互作用的强度,从而导致结构的垂直磁化曲线矫顽力大小发生改变.这项研究将对基于AlOx氧化层垂直磁隧道结的研制具有重要的意义.

The perpendicular magnetic anisotropy （PMA） of the CoFeB/AlOx/Ta structure and the AlOx/CoFeB/Ta structure with different thicknesses of both CoFeB and AlOx is studied. Magnetization curves show that the CoFeB/AlOx/Ta structure has a clear perpendicular magnetic easy axis while the AlOx/CoFeB/Ta structure does not. The cause of the asymmetrical phenomenon in the symmetric structures is analyzed. Dependence of the perpendicular coercivities on the thicknesses of CoFeB and AlOx shows that both of them can affect the strength of the PMA originating from the interfacial interaction. This work will be meaningful for the fabrication of the AlOx-based perpendicular magnetic tunnel junctions.