Effect of alignment of easy axes on dynamic magnetization of immobilized magnetic nanoparticles
Effect of alignment of easy axes on dynamic magnetization of immobilized magnetic nanoparticles
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DOI：
10.1016/j.jmmm.2016.10.040
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发表时间：
2017-04-01
影响因子：
2.7
通讯作者：
Ludwig, Frank
中科院分区：
文献类型：
--
作者：
Yoshida, Takashi;Matsugi, Yuki;Ludwig, Frank
在磁性纳米颗粒（MNP）的一些生物医学应用中，颗粒被物理固定。在这项研究中，我们探讨了固定化MNPs在交流激励场下的动态磁化的磁易轴的对齐的效果。我们制备了三种固定化的MNP样品：（1）易磁化轴随机取向的样品，（2）易磁化轴平行于AC场的平行排列样品，和（3）易磁化轴垂直于AC场的正交排列样品。首先，我们表明，平行排列的样品具有最大的磁滞磁化曲线和最大的谐波磁化谱，其次是随机取向和正交排列的样品。例如，与随机取向的样品相比，在平行排列的样品的滞后回线的面积中观察到1.6倍的增加。为了定量地讨论实验结果，我们进行了数值模拟的基础上的福克-普朗克方程，其中考虑到在模拟制备的MNP样品的易轴的方向的概率分布。我们得到了定量的实验和模拟之间的协议。这些结果表明，固定化MNPs的动态磁化强度显着影响的易轴的排列。
In some biomedical applications of magnetic nanoparticles (MNPs), the particles are physically immobilized. In this study, we explore the effect of the alignment of the magnetic easy axes on the dynamic magnetization of immobilized MNPs under an AC excitation field. We prepared three immobilized MNP samples: (1) a sample in which easy axes are randomly oriented, (2) a parallel-aligned sample in which easy axes are parallel to the AC field, and (3) an orthogonally aligned sample in which easy axes are perpendicular to the AC field. First, we show that the parallel-aligned sample has the largest hysteresis in the magnetization curve and the largest harmonic magnetization spectra, followed by the randomly oriented and orthogonally aligned samples. For example, 1.6fold increase was observed in the area of the hysteresis loop of the parallel-aligned sample compared to that of the randomly oriented sample. To quantitatively discuss the experimental results, we perform a numerical simulation based on a Fokker-Planck equation, in which probability distributions for the directions of the easy axes are taken into account in simulating the prepared MNP samples. We obtained quantitative agreement between experiment and simulation. These results indicate that the dynamic magnetization of immobilized MNPs is significantly affected by the alignment of the easy axes.