arXiv 1909.106432019-09-23cond-mat.mtrl-scicond-mat.mes-hall

$Co_{x}Fe_{3-x}O_{4}$纳米粒子的有效宏观自旋模型：通过共掺杂降低各向异性？

Effective macrospin model for $Co_{x}Fe_{3-x}O_{4}$ nanoparticles: decreasing the anisotropy by Co-doping?

David Serantes, Daniel Faílde, Daniel Baldomir, Beatriz Pelaz, Pablo del Pino, Roy W. Chantrell

备注：: 6 pages, 7 figures

摘要：

$Co$ -$Fe_{3}O_{4}$磁性纳米颗粒的掺杂是定制其磁性的有效方式。当考虑$Co_{x}Fe_{3-x}O_{4}$系列的两个极端情况，即$x=0$和$x=1$值时，发现系统从负的各向异性能量常数$K_{C}^{-}<0$演化到正的$K_{C}^{+}>0$。因此，中间体PDMATHAMT组合物会发生什么？在这项工作中，我们提出了一个非常简单的唯象模型的各向异性，下的\textit{macrospin}近似，其中所得到的各向异性是直接成比例的量的$Co$。首先，我们进行了详细的分析，在一个相当理想的系统，其中的极值具有相同的幅度（即$|K_{C}^{-}|=|K_{C}^{+}|$），然后我们专注于真正的$Co_{x}Fe_{3-x}O_{4}$系统，其中$|K_{C}^{+}|\sim 18|K_{C}^{-}|$。值得注意的是，该方法相当好地再现了$Co_{x}Fe_{3-x}O_{4}$纳米粒子的加热性能的实验值，这表明我们的简单方法实际上可能是真实情况的良好代表。这引起了一种有趣的相关可能性：$Co$掺杂组合物应该存在，其有效各向异性趋于零，在此估计为0.05。

英文摘要：

$Co$-doping of $Fe_{3}O_{4}$ magnetic nanoparticles is an effective way to tailor their magnetic properties. When considering the two extreme cases of the $Co_{x}Fe_{3-x}O_{4}$ series, i.e. the $x=0$ and $x=1$ values, one finds that the system evolves from a negative cubic-anisotropy energy constant, $K_{C}^{-}<0$, to a positive one, $K_{C}^{+}>0$. Thus, what happens for intermediate $x$-compositions? In this work we present a very simple phenomenological model for the anisotropy, under the \textit{macrospin} approximation, in which the resultant anisotropy is just directly proportional to the amount of $Co$. First, we perform a detailed analysis on a rather ideal system in which the extreme values have the same magnitude (i.e. $|K_{C}^{-}|=|K_{C}^{+}|$) and then we focus on the real $Co_{x}Fe_{3-x}O_{4}$ system, for which $|K_{C}^{+}|\sim 18|K_{C}^{-}|$. Remarkably, the approach reproduces rather well the experimental values of the heating performance of $Co_{x}Fe_{3-x}O_{4}$ nanoparticles, suggesting that our simple approach may in fact be a good representation of the real situation. This gives rise to an intriguing related possibility arises: a $Co$-doping composition should exist for which the effective anisotropy tends to zero, estimated here as 0.05.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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英文摘要：

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