Magnetic nanoparticles with combined anisotropy
Magnetic nanoparticles with combined anisotropy
复制标题
具有组合各向异性的磁性纳米颗粒
DOI：
10.1063/1.4749799
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发表时间：
2012
影响因子：
3.2
通讯作者：
J. Barandiaran
中科院分区：
文献类型：
--
作者：
N. Usov;J. Barandiaran
我们研究了颗粒长径比的分布对具有立方磁晶各向异性的纳米颗粒（例如铁、镍、铁氧化物和铁氧体）的静磁性能的影响。由于无量纲比 Ms2/|Kc| 的值很大对于这些粒子，即使形状畸变相对较小，形状各向异性能量对总纳米粒子能量也有相当大的贡献，等效椭球的长宽比为 xi ≥ 1.1。因此，具有组合各向异性的随机取向颗粒集合体在 xi ≥ 1.1 时的静磁特性与具有纯单轴磁各向异性的颗粒集合体的静磁特性相似。该结论不仅对于组件磁滞回线有效，而且对于磁弛豫特性也有效，至少在高阻尼极限下如此。
We study the influence of the distribution of the particles' aspect ratio on the magnetostatic properties of an assembly of nanoparticles with cubic magnetocrystalline anisotropy, such as iron, nickel, iron oxides, and ferrites. Because of the large values of the dimensionless ratio Ms2/|Kc| for these particles, the shape anisotropy energy makes considerable contribution to the total nanoparticle energy even for relatively small shape distortions, with equivalent ellipsoids having aspect ratios ξ ≥ 1.1. As a result, the magnetostatic properties of a randomly oriented assembly of particles with combined anisotropy at ξ ≥ 1.1 are similar to those for an assembly of particles with purely uniaxial magnetic anisotropy. This conclusion is shown to be valid not only for the assembly hysteresis loops but also for the magnetic relaxation characteristics, at least in the high damping limit.