Effective energy barrier distributions for random and aligned magnetic nanoparticles.
Effective energy barrier distributions for random and aligned magnetic nanoparticles.
复制标题
随机和排列磁性纳米颗粒的有效能垒分布。
DOI：
10.1088/0953-8984/26/14/146006
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Eloi JC
中科院分区：
文献类型：
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作者：
Eloi JC
等温磁弛豫测量广泛用于探测磁性纳米颗粒系统中的能垒。在这里，我们表明，对于排列和随机取向的纳米颗粒，此类实验的结果可能有很大差异。对于随机取向的钴掺杂磁铁矿纳米颗粒，我们观察到能垒分布中存在显着的低能尾部，当颗粒磁性排列时，该尾部会大大衰减。蒙特卡罗模拟表明，对于具有立方和单轴磁各向异性能量项的纳米颗粒，即使对于单独的立方或单轴各向异性，能垒分布与纳米颗粒方向无关，也会出现这种行为。
Isothermal magnetic relaxation measurements are widely used to probe energy barriers in systems of magnetic nanoparticles. Here we show that the result of such an experiment can differ greatly for aligned and randomly oriented nanoparticles. For randomly oriented cobalt-doped magnetite nanoparticles we observe a prominent low-energy tail in the energy barrier distribution that is greatly attenuated when the particles are magnetically aligned. Monte Carlo simulations show that this behaviour arises for nanoparticles with both cubic and uniaxial magnetic anisotropy energy terms even though for cubic or uniaxial anisotropy alone the energy barrier distribution is independent of nanoparticle orientation.