Effect of FePd alloy composition on the dynamics of artificial spin ice.
Effect of FePd alloy composition on the dynamics of artificial spin ice.
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DOI：
10.1038/s41598-018-23208-6
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发表时间：
2018-03-19
影响因子：
4.6
通讯作者：
Marrows CH
中科院分区：
文献类型：
--
作者：
Morley SA;Riley ST;Porro JM;Rosamond MC;Linfield EH;Cunningham JE;Langridge S;Marrows CH
人工自旋冰（ASI）是单畴纳米磁性岛阵列，其几何形状排列会引起静磁相互作用的挫败。可以通过热退火达到它们的基态。我们使用不同的FePd合金通过共溅射来改变磁化强度，从而制成方形ASI。从一个极化状态的样品被逐步加热，我们测量的顶点人口作为温度的函数，使用磁力显微镜。对于更高的磁化FePd样品，我们报告了在T = 493 K时的动力学开始，快速坍缩到>90%的基态顶点。相比之下，低磁化强度样品在较低的温度下开始波动，T = 393 K，并在更宽的温度范围内，但仅达到基态顶点的25%的最大值。这些结果表明，相互作用的强度，动态温度范围和途径，可以微调使用一个简单的共溅射过程。此外，我们已经比较了我们的实验值的阻塞温度的预测使用简单的Néel-Brown两态模型，发现一个很大的差异，我们归因于激活体积远小于岛体积。
Artificial spin ices (ASI) are arrays of single domain nano-magnetic islands, arranged in geometries that give rise to frustrated magnetostatic interactions. It is possible to reach their ground state via thermal annealing. We have made square ASI using different FePd alloys to vary the magnetization via co-sputtering. From a polarized state the samples were incrementally heated and we measured the vertex population as a function of temperature using magnetic force microscopy. For the higher magnetization FePd sample, we report an onset of dynamics at T = 493 K, with a rapid collapse into >90% ground state vertices. In contrast, the low magnetization sample started to fluctuate at lower temperatures, T = 393 K and over a wider temperature range but only reached a maximum of 25% of ground state vertices. These results indicate that the interaction strength, dynamic temperature range and pathways can be finely tuned using a simple co-sputtering process. In addition we have compared our experimental values of the blocking temperature to those predicted using the simple Néel-Brown two-state model and find a large discrepancy which we attribute to activation volumes much smaller than the island volume.
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