Tunnel Magnetoresistance in Full-Heusler Co2FeAl0.5Si0.5-Based Magnetic Tunnel Junctions
Tunnel Magnetoresistance in Full-Heusler Co2FeAl0.5Si0.5-Based Magnetic Tunnel Junctions
复制标题
全赫斯勒 Co2FeAl0.5Si0.5 基磁隧道结中的隧道磁阻
DOI：
10.3379/msjmag.0903re8037
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发表时间：
2009
影响因子：
--
通讯作者：
K. Inomata
中科院分区：
文献类型：
--
作者：
H. Sukegawa;W. Wang;R. Shan;K. Inomata
采用溅射法制备了具有全Heusler Co2FeAl0.5Si0.5（CFAS）电极的全外延磁性隧道结（MTJ）。我们改变了MgO阻挡层厚度、插入CFAS和MgO层之间的Mg层的厚度以及CFAS层的后退火工艺，以获得实现高隧道磁阻（TMR）比所需的条件。我们发现，MgO势垒厚度和后退火温度直接影响TMR比，而薄Mg层插入没有。在高于873 K的较高温度下的后退火抑制了TMR比，这是由于在后退火期间顶部CFAS层的结构的退化。此外，由于MgO阻挡层的质量差，在我们的MTJ中观察到大的有效隧道势垒高度。这些事实表明，CFAS/MgO界面的隧穿自旋极化不仅对CFAS中L21或B2的有序程度敏感，而且对MgO势垒和CFAS/MgO界面的质量也敏感。
We fabricated fully epitaxial magnetic tunnel junctions (MTJs) with full-Heusler Co2FeAl0.5Si0.5 (CFAS) electrodes using the sputtering method. We changed the MgO barrier thickness, the thickness of an Mg layer inserted between the CFAS and MgO layers, and a post-annealing process for CFAS layers in order to obtain conditions necessary for achieving a high tunnel magnetoresistance (TMR) ratio. We found that both the MgO barrier thickness and the post-annealing temperature directly influenced the TMR ratio while the thin Mg layer insertion did not. Post-annealing at higher temperatures above 873 K suppresses the TMR ratio due to degradation of the structure of top CFAS layer during the post-annealing. In addition, a large effective tunnel barrier height was observed in our MTJs because of the poor quality of MgO barrier layer. These facts indicate that the tunneling spin polarization of CFAS/MgO interface is sensitive not only to the degree of ordering of L21 or B2 in CFAS but also to the quality of the MgO barrier and CFAS/MgO interfaces.