Evolution of the interfacial perpendicular magnetic anisotropy constant of the Co2FeAl/MgO interface upon annealing
Evolution of the interfacial perpendicular magnetic anisotropy constant of the Co2FeAl/MgO interface upon annealing
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DOI：
10.1088/1361-6463/aab5d8
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发表时间：
2017-08
期刊：
影响因子：
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通讯作者：
A. Conca;A. Niesen;G. Reiss;B. Hillebrands
中科院分区：
文献类型：
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作者：
A. Conca;A. Niesen;G. Reiss;B. Hillebrands
我们研究了一系列不同厚度的 Heusler 合金 Co2FeAl 薄膜，以研究退火对 MgO 层界面以及体磁性能的影响。我们的结果表明，虽然沉积态样品的垂直界面各向异性常数 KS⊥ 为零，但由于热处理过程中界面发生了强烈的改性，其值随着退火而增加，对于 320 °C 退火的系列，其值增加至 1.14±0.07 mJ m−2，对于 450 °C 退火的系列，其值增加至 2.01±0.7 mJ m−2。这个大值确保了外推厚度低于 1.7 nm 时垂直磁化方向的稳定性。数据还表明，在沉积态和退火态系统中，面内双轴各向异性常数随厚度的变化而变化。吉尔伯特阻尼参数 α 显示厚度为 40 nm 时所有系列的最小值和 2.8±0.1×10−3 的绝对最小值。厚度依赖性可以用系统不同各向异性之间的相互作用和晶体无序产生的不均匀磁化状态来解释。
We investigate a series of films with different thickness of the Heusler alloy Co2FeAl in order to study the effect of annealing on the interface with a MgO layer and on the bulk magnetic properties. Our results reveal that while the perpendicular interface anisotropy constant KS⊥ is zero for the as-deposited samples, its value increases with annealing up to a value of 1.14±0.07 mJ m−2 for the series annealed at 320 °C and of 2.01±0.7 mJ m−2 for the 450 °C annealed series owing to a strong modification of the interface during the thermal treatment. This large value ensures a stabilization of a perpendicular magnetization orientation for an extrapolated thickness below 1.7 nm. The data additionally shows that the in-plane biaxial anisotropy constant has a different evolution with thickness in as-deposited and annealed systems. The Gilbert damping parameter α shows minima for all series for a thickness of 40 nm and an absolute minimum value of 2.8±0.1×10−3. The thickness dependence is explained in terms of an inhomogeneous magnetization state generated by the interplay between the different anisotropies of the system and by the crystalline disorder.