Structural characterizations of Co2MnSi/MgO/Co2MnSi magnetic tunnel junctions by transmission electron microscopy
Structural characterizations of Co2MnSi/MgO/Co2MnSi magnetic tunnel junctions by transmission electron microscopy
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DOI：
10.1016/j.jmmm.2009.09.059
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发表时间：
2010-02
影响因子：
2.7
通讯作者：
T. Nakatani;Y. Takahashi;T. Ishikawa;Masafumi Yamamoto;K. Hono
中科院分区：
文献类型：
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作者：
T. Nakatani;Y. Takahashi;T. Ishikawa;Masafumi Yamamoto;K. Hono
我们研究了Co2 MnSi/MgO/Co2 MnSi磁性隧道结的结构，其隧道磁电阻值取决于上Co2 MnSi电极沉积后的原位退火温度。纳米束衍射图表明，在550°C退火的Co2 MnSi电极的有序度高于在400°C退火的电极。此外，在550°C下退火的上部Co2 MnSi电极的L21有序度甚至低于在几乎相同的温度600°C下退火的下部Co2 MnSi电极的L21有序度。采用高角度环形暗场（HAADF）方法进行的原子尺度观测清楚地表明，在400°C退火的Co2 MnSi电极上，B2有序基体中存在L21有序区域。
We have investigated the structure of Co2MnSi/MgO/Co2MnSi magnetic tunneling junctions with different tunnel magnetoresistance values depending on the in situ annealing temperatures just after the deposition of the upper Co2MnSi electrodes. The nano-beam diffraction patterns indicated that the degree of order of the upper Co2MnSi electrode annealed at 550°C was higher than that of an electrode annealed at 400°C. Moreover, the degree of the L21order of the upper Co2MnSi electrode annealed at 550°C was even lower than that of the lower Co2MnSi electrode annealed at an almost equal temperature of 600°C. Atomic-scale observation using a high-angle annular dark-field (HAADF) method distinctly showed the existence of the L21-ordered regions in the B2-ordered matrix in the upper Co2MnSi electrode annealed at 400°C.