Particle blocking and carrier fluid freezing effects on the magnetic properties of Fe3O4-based ferrofluids
Particle blocking and carrier fluid freezing effects on the magnetic properties of Fe3O4-based ferrofluids
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DOI：
10.1063/1.3068461
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发表时间：
2009-04-01
影响因子：
3.2
通讯作者：
Srikanth, H.
中科院分区：
文献类型：
--
作者：
Morales, M. B.;Phan, M. H.;Srikanth, H.
本文系统地研究了纳米Fe3O4颗粒(平均尺寸约14 nm)悬浮在正己烷和十二烷中的两种不同磁流体中粒子堵塞和载流冻结对磁化和弛豫过程的直流和交流磁化率的影响，这两种磁性流体的冻结温度分别低于(178K)和高于(264K)磁性纳米颗粒的阻塞温度(类似于200K)。实验结果表明，这些效应在磁流体中玻璃峰和磁异常的形成中起着关键作用。Vogel-Fulcher模型tau=tau(O)exp[E-a/k(T-T-o)]的频率相关交流磁化率的定量拟合清楚地表明，冻结状态下磁性纳米粒子的阻塞显著地影响了粒子间的偶极-偶极相互作用，导致了特征的自旋玻璃动力学。(C)2009年美国物理研究所。[DOI：10.1063/1.3068461]
We report the systematic dc and ac susceptibility studies on the particle blocking and carrier fluid freezing effects on the magnetization and relaxation processes in two different ferrofluids composed of Fe3O4 nanoparticles (mean size of similar to 14 nm) suspended in hexane and dodecane, which respectively have freezing temperatures below (178 K) and above (264 K) the blocking temperature of magnetic nanoparticles (similar to 200 K). Experimental results reveal that these effects play a key role in the formation of glasslike peaks and magnetic anomalies in ferrofluids. Quantitative fits of the frequency dependent ac susceptibility to the Vogel-Fulcher model tau=tau(o) exp[E-a/k(T-T-o)] clearly indicate that the blocking of magnetic nanoparticles in the frozen state significantly affects the interparticle dipole-dipole interaction, causing characteristic spin-glass-like dynamics. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3068461]