Modestino Michele, Galluzzi Armando, Sarno Maria, Polichetti Massimiliano
Department of Physics "E.R. Caianiello", University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, SA, Italy.
CNR-SPIN Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, SA, Italy.
Materials (Basel). 2023 Jun 8;16(12):4246. doi: 10.3390/ma16124246.
The AC magnetic properties of a sample of FeO nanoparticles coated with oleic acid have been investigated with the help of AC susceptibility measurements. In particular, several DC magnetic fields have been superimposed on the AC field, and their effect on the magnetic response of the sample has been analysed. The results show the presence of a double peak structure in the imaginary component of the complex AC susceptibility measured as a function of the temperature. A preliminary evaluation of the Mydosh parameter for both peaks gives the information that each one of them is associated with a different state of interaction between nanoparticles. The two peaks evolve both in amplitude and position when the intensity of the DC field is changed. The field dependence of the peak position shows two different trends, and it is possible to study them in the framework of the currently existing theoretical models. In particular, a model of non-interacting magnetic nanoparticles has been used to describe the behaviour of the peak at lower temperatures, whereas the behaviour of the peak at higher temperatures has been analysed in the framework of a spin-glass-like model. The proposed analysis technique can be useful for the characterisation of magnetic nanoparticles used in several types of applications, such as biomedical and magnetic fluids.
借助交流磁化率测量，研究了涂有油酸的FeO纳米颗粒样品的交流磁特性。特别地，在交流场上叠加了几个直流磁场，并分析了它们对样品磁响应的影响。结果表明，在作为温度函数测量的复交流磁化率的虚部中存在双峰结构。对两个峰的米多什参数进行初步评估，得出的信息是，它们中的每一个都与纳米颗粒之间不同的相互作用状态相关。当直流场强度改变时，两个峰的幅度和位置都会发生变化。峰位置的场依赖性呈现出两种不同的趋势，可以在现有理论模型的框架内对其进行研究。特别地，已使用非相互作用磁性纳米颗粒模型来描述较低温度下峰的行为，而较高温度下峰的行为则在类似自旋玻璃的模型框架内进行了分析。所提出的分析技术可用于表征用于多种类型应用（如生物医学和磁性流体）的磁性纳米颗粒。
