We investigated the static and dynamic magnetic properties of Zn0.4Fe2.6O4 nanoparticles synthesized by thermal decomposition. Two ranges of diameter were used: small particles (diameter about 6.2 nm) and larger ones (diameter about 22.4 nm). The nanoparticle microstructure was characterized by transmission electron microscopy. The temperature dependence of the zero-field dynamic permeability for both nanoparticle sizes was studied, revealing a superparamagnetic state for the small ones. Effects of the nanoparticle size on the dynamic permeability were analyzied, and linked to the superparamagnetic state. A dynamic susceptibility model was found to reproduce the experimental behavior as well as its temperature dependence.

中文翻译：

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亚铁磁性纳米粒子零场微波磁化率谱中超顺磁性状态的证据

我们研究了通过热分解合成的 Zn0.4Fe2.6O4 纳米颗粒的静态和动态磁性能。使用了两个直径范围：小颗粒（直径约 6.2 nm）和较大颗粒（直径约 22.4 nm）。通过透射电子显微镜表征纳米颗粒微结构。研究了两种纳米颗粒尺寸的零场动态磁导率的温度依赖性，揭示了小颗粒的超顺磁性状态。分析了纳米颗粒尺寸对动态磁导率的影响，并将其与超顺磁性状态联系起来。发现动态磁化率模型可以再现实验行为及其温度依赖性。