Increased tunneling magnetoresistance using normally bcc CoFe alloy electrodes made amorphous without glass forming additives.
Increased tunneling magnetoresistance using normally bcc CoFe alloy electrodes made amorphous without glass forming additives.
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DOI：
10.1103/physrevlett.102.247205
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发表时间：
2009-06
影响因子：
8.6
通讯作者：
Li Gao;Xin Jiang;See-Hun Yang;P. Rice;T. Topuria;S. Parkin
中科院分区：
文献类型：
--
作者：
Li Gao;Xin Jiang;See-Hun Yang;P. Rice;T. Topuria;S. Parkin
使用横截面透射电子显微镜，我们表明，薄膜的CoFe合金，夹在两个传统的非晶材料，是非晶时，小于约25-30埃厚。当这些非晶层被集成到具有非晶氧化铝隧道势垒的磁性隧道结中时，发现与当这些层被制成晶体时相比显著更高的隧穿磁阻（例如，通过加热或通过使它们变稠）。我们推测，这可能是由于在氧化铝-CoFe界面的界面结合的变化。事实上，X-射线发射光谱显示出显着增加的Fe，但不是Co，3d态密度在费米能量薄的非晶CoFe层。
Using cross-section transmission electron microscopy we show that films of CoFe alloys, sandwiched between two conventional amorphous materials, are amorphous when less than approximately 25-30 A thick. When these amorphous layers are integrated into magnetic tunnel junctions with amorphous alumina tunnel barriers, significantly higher tunneling magnetoresistance is found compared to when these layers are made crystalline (e.g., by heating or by thickening them). We postulate that this is likely due to changes in interfacial bonding at the alumina-CoFe interface. Indeed, x-ray emission spectroscopy shows a significant increase in the Fe, but not the Co, 3d density of states at the Fermi energy for thin amorphous CoFe layers.