Correlation of tunnel magnetoresistance with the magnetic properties in perpendicular CoFeB-based junctions with exchange bias
Correlation of tunnel magnetoresistance with the magnetic properties in perpendicular CoFeB-based junctions with exchange bias
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DOI：
10.1063/1.5062847
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发表时间：
2019-01-14
影响因子：
3.2
通讯作者：
Reiss, Guenter
中科院分区：
文献类型：
--
作者：
Manos, Orestis;Bougiatioti, Panagiota;Reiss, Guenter
在一系列材料的垂直磁隧道结序列Ta/Pd/IrMn/CoFe/Ta(x)/CoFeB/MgO(y)/CoFeB(z)/Ta/Pd.中，研究了磁特性与后退火温度/时间、软铁磁电极厚度和钉扎电极中Ta粉尘层的关系以及它们与隧道磁阻比的关系当x=0.3 nm时，我们得到了79.6kA/m的大垂直交换偏置。对于z=1.05 nm的叠层，软电极的磁特性类似于超顺磁性。对于x=0.4 nm，y=2 nm，z=1.20 nm的叠层，当退火温度T-ann=330℃，60min时，交换偏置显著减小，而层间交换耦合和单位面积饱和磁化强度在T-ann=340℃，60min急剧下降。同时，在T-ann=300℃下退火60min后，隧道磁电阻率出现峰值65.5%，较高的退火温度(T-ann>；=330℃)显著降低到10%，较长的退火时间(T-ann=300℃，90min)下降到14%。我们将隧道磁阻比的大幅降低归因于钉扎电极中交换偏置的损失。由AIP出版公司授权出版。
We investigate the dependence of magnetic properties on the post-annealing temperature/time, the thickness of the soft ferromagnetic electrode, and the Ta dusting layer in the pinned electrode as well as their correlation with the tunnel magnetoresistance ratio, in a series of perpendicular magnetic tunnel junctions of materials sequence Ta/Pd/IrMn/CoFe/Ta(x)/CoFeB/MgO(y)/CoFeB(z)/Ta/Pd. We obtain a large perpendicular exchange bias of 79.6 kA/m for x = 0.3 nm. For stacks with z = 1.05 nm, the magnetic properties of the soft electrode resemble the characteristics of superparamagnetism. For stacks with x = 0.4 nm, y = 2 nm, and z = 1.20 nm, the exchange bias presents a significant decrease at post-annealing temperature T-ann = 330 degrees C for 60 min, while the interlayer exchange coupling and the saturation magnetization per unit area sharply decay at T-ann = 340 degrees C for 60 min. Simultaneously, the tunnel magnetoresistance ratio shows a peak of 65.5% after being annealed at T-ann = 300 degrees C for 60 min, with a significant reduction down to 10% for higher annealing temperatures (T-ann >= 330 degrees C) and down to 14% for longer annealing times (T-ann = 300 degrees C for 90 min). We attribute the large decrease of tunnel magnetoresistance ratio to the loss of exchange bias in the pinned electrode. Published under license by AIP Publishing.