High thermal stability tunnel junctions
High thermal stability tunnel junctions
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DOI：
10.1063/1.372611
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发表时间：
2000-05-01
影响因子：
3.2
通讯作者：
Soares, JC
中科院分区：
文献类型：
--
作者：
Cardoso, S;Freitas, PP;Soares, JC
研究了离子束采用两种氧化方法制备的 CoFe/Al2O3/CoFe/MnIr 自旋隧道结的热稳定性，退火温度高达 450 摄氏度。300 摄氏度退火后，隧道磁阻 (TMR) 为 40%，380 摄氏度退火后，TMR 仍达到 15%。退火时 TMR 衰减取决于氧化过程。 （O-2 束或远程等离子体）和 MnIr 交换层的厚度。在氧化过程中，Al 的过度氧化或 O-2 离子的较高动能会导致 TMR 更快的热降解。较薄的 MnIr 可延缓热降解。卢瑟福背向散射显示，在 300 摄氏度以上，Mn 强烈相互扩散到 CoFe 电极中，但即使在 435 摄氏度退火后，CoFe/Al2O3/CoFe 界面也没有检测到显着变化（结电阻仍然很高，证实了势垒稳定性）。正如 Mn 掺入所预期的那样，退火后固定层力矩会降低。此外，TMR 的强烈下降可能表明当 Mn 到达 Al2O3/CoFe 界面时极化损耗。在410℃时，TMR仍为5%，自由层的快速开关特性不变。 (C) 2000 年美国物理研究所。 [S0021-8979(00)42908-7]。
The thermal stability of CoFe/Al2O3/CoFe/MnIr spin-tunnel junctions fabricated by ion beam, using two oxidation methods is studied for annealing temperatures up to 450 degrees C. Tunnel magnetoresistance (TMR) is 40% after annealing at 300 degrees C, and a TMR of 15% is still achieved after annealing at 380 degrees C. The TMR decay with anneal depends on the oxidation process (O-2 beam or remote plasma) and on the thickness of the MnIr exchange layer. Overoxidation of the Al, or higher kinetic energy of the O-2 ions, during oxidation, lead to faster thermal degradation of the TMR. Thinner MnIr retards thermal degradation. Rutherford backscattering shows a strong interdiffusion of Mn into the CoFe electrode above 300 degrees C, but no significant changes are detected at the CoFe/Al2O3/CoFe interfaces, even after annealing at 435 degrees C (the junction resistance remains high confirming barrier stability). The pinned layer moment decreases upon annealing as expected from Mn incorporation. Also, the strong TMR decrease may indicate polarization loss when Mn reaches the Al2O3/CoFe interface. At 410 degrees C, the TMR is still 5%, with the fast switching characteristics of the free layer unchanged. (C) 2000 American Institute of Physics. [S0021-8979(00)42908-7].