Superparamagnetic and ferrimagnetic resonance of ultrafine Fe3O4 particles in ferrofluids
Superparamagnetic and ferrimagnetic resonance of ultrafine Fe3O4 particles in ferrofluids
复制标题
铁磁流体中超细 Fe3O4 颗粒的超顺磁和亚铁磁共振
DOI：
10.1063/1.323418
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发表时间：
1977
影响因子：
3.2
通讯作者：
F. Waldner
中科院分区：
文献类型：
--
作者：
Vikas Sharma;F. Waldner
在室温下用电子磁共振研究了五种磁性液体（商品“铁磁流体”）中包覆的超细磁铁矿颗粒（平均直径约100 A）。窄信号可归因于颗粒的超顺磁性部分。一个简单的“超顺磁窄化”模型与测量结果一致。铁磁性部分给出一条宽线。两条谱线在稀释时变窄，因为粒子间偶极相互作用减少。粘度的变化对信号的影响很小。在三氟乙酸中稀释似乎会破坏涂层。由此产生的凝聚和沉淀极大地改变了磁共振。立方各向异性常数K1的高值的原因？（-5.8 ×105 erg/cm ~ 3）的超微粒子的电子结构。
Coated ultrafine magnetite particles (average diameter around 100 A) in five nonmagnetic liquids (commercial ’’ferrofluids’’) have been investigated by electron magnetic resonance at room temperature. A narrow signal can be attributed to the superparamagnetic fraction of the particles. A simple ’’superparamagnetic narrowing’’ model is consistent with the measurements. The ferromagnetic fraction gives a broad line. Both lines narrow upon dilution because the interparticle dipolar interaction is reduced. Variations of the viscosity have only minor effects on the signals. Dilution in trifluoroacetic acid seems to destroy the coating. The resulting agglomeration and sedimentation changes the magnetic resonance drastically. The reasons for the high value of the cubic anisotropy constant K1? (−5.8×105 erg/cm3) found for the ultrafine particles are discussed.