Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers
Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers
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DOI：
10.1063/1.4927638
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发表时间：
2015-07
期刊：
影响因子：
1.6
通讯作者：
J. Rogge;W. Hetaba;J. Schmalhorst;H. Bouchikhaoui;P. Stender;D. Baither;G. Schmitz;A. Hütten
中科院分区：
文献类型：
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作者：
J. Rogge;W. Hetaba;J. Schmalhorst;H. Bouchikhaoui;P. Stender;D. Baither;G. Schmitz;A. Hütten
我们成功地将BaO作为隧道势垒集成到Co_2FeAl基磁性隧道结中。通过俄歇电子能谱，可以证明，在BaO沉积期间和之后施加的退火温度不会导致Ba扩散到下部Heusler化合物铅中或上部Fe对电极中。然而，对于Co_2FeAl（24 nm）/ BaO（5 nm）/ Fe（7 nm）MTJ，发现负的隧道磁电阻（TMR）比为~ 10%，这可以归因于制备过程，并且可以通过与理论比较在Heusler和结晶BaO势垒之间的界面处形成Co和Fe氧化物来解释。虽然高分辨率透射电子显微镜（TEM）证实了BaO屏障的无定形结构，但由于BaO对水分的敏感性，不能完全排除这是TEM样品制备的伪影。通过用MgO/BaO双层结构代替BaO隧穿势垒，
We succeed to integrate BaO as a tunneling barrier into Co2FeAl based magnetic tunnel junctions (MTJs). By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR) ratio of -10% is found for Co2FeAl (24 nm) / BaO (5 nm) / Fe (7 nm) MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM), it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double lay...