Nanotechnology. 2014 Jan 31;25(4):045604. doi: 10.1088/0957-4484/25/4/045604.
We studied exchange coupled composite (ECC) media with an out-of-plane easy axis consisting of hard magnetic L1(0) chemically ordered FePtCu alloy films and magnetically softer Co/Pt multilayer stacks. By tailoring the structural properties of the ternary FePtCu alloy and Co/Pt multilayers, we can tune the magnetic parameters of the composite in a wide range. This allowed us to address experimentally one of the most crucial properties determining the performance of ECC media, namely the pinning field of the magnetic domain wall present at the interface between the hard and soft layers. We demonstrate that the pinning field is proportional to the difference of the magnetic anisotropy constants of the hard and soft layers, which confirms the theoretical predictions. Furthermore, we show that the pinning field can be efficiently decreased after an additional annealing step. Transmission electron microscopy investigations indicated that the origin of the observed effect is due to a heat-induced phase transformation of iron oxide present at the interface between the hard and soft layers. This study reveals that tailoring the properties of the hard/soft interface is another efficient tuning knob for optimization of the performance of ECC media.
我们研究了具有面外易轴的交换耦合复合（ECC）介质，该易轴由硬磁 L1(0)化学有序 FePtCu 合金薄膜和磁性较软的Co/Pt多层堆叠组成。通过调整三元 FePtCu 合金和Co/Pt多层的结构特性，我们可以在很宽的范围内调整复合介质的磁性参数。这使我们能够在实验上解决决定 ECC 介质性能的最关键特性之一，即存在于硬层和软层之间的磁畴壁的钉扎场。我们证明，钉扎场与硬层和软层的磁各向异性常数之差成正比，这证实了理论预测。此外，我们表明，在额外的退火步骤后，钉扎场可以有效地降低。透射电子显微镜研究表明，观察到的效应的起源是由于硬软层之间界面处存在的氧化铁的热诱导相变。这项研究表明，调整硬/软界面的性质是优化 ECC 介质性能的另一个有效调节旋钮。
