Linear and cubic dynamic susceptibilities of superparamagnetic fine particles
Linear and cubic dynamic susceptibilities of superparamagnetic fine particles
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DOI：
10.1103/physrevb.55.15005
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发表时间：
1997-06-01
影响因子：
3.7
通讯作者：
Stepanov, VI
中科院分区：
文献类型：
--
作者：
Raikher, YL;Stepanov, VI
提出了单轴各向异性非相互作用细磁性颗粒组件的线性和非线性（三次）初始磁化率的一致理论。静态（平衡）磁化率的表达式直接从相关统计热力学获得。各向异性的贡献仍以一阶形式出现，并针对随机分布和轴对齐分布进行分析。基于微磁福克-普朗克方程研究了交流磁化率。给出了任意频率的数值精确解和可靠的低频近似。与基于常规超顺磁阻塞模型的描述相比，获得的描述更加准确。结果用于对最近发表的 Co-Cu 沉淀合金数据集进行定量解释。就此而言，讨论了颗粒尺寸分布函数的选择。
A consistent theory of linear and nonlinear (cubic) initial susceptibilities of an assembly of uniaxially anisotropic noninteracting fine magnetic particles is presented. The expressions for the static (equilibrium) susceptibilities are obtained directly from the pertinent statistical thermodynamics. The contributions of anisotropy emerge yet in the first order and are analyzed for random and axes-aligned distributions. The ac susceptibilities are studied on the basis of the micromagnetic Fokker-Planck equation. Both a numerically exact solution for arbitrary frequency and a reliable low-frequency approximation are given. The obtained description Droves to be more accurate as compared to the one based on the customary superparamagnetic blocking model. The results are used for a quantitative interpretation of recently published set of data on Co-Cu precipitating alloys. In this connection the choice of the particle size-distribution function is discussed.