Thermal evolution of the magnetization in nanocrystalline Fe particles investigated by electron holography
Thermal evolution of the magnetization in nanocrystalline Fe particles investigated by electron holography
复制标题
通过电子全息技术研究纳米晶铁颗粒磁化强度的热演化
DOI：
10.1063/1.1401797
复制
发表时间：
2001
影响因子：
3.2
通讯作者：
S. Signoretti
中科院分区：
文献类型：
--
作者：
E. Bonetti;L. Bianco;L. Pasquini;G. Matteucci;C. Beeli;S. Signoretti
采用机械研磨的方法，通过球磨制备了具有纳米晶结构的微米、不规则形状的铁粉。用电子全息术观察了孤立的Fe粒子在300K和选定温度T⩽1200 K下产生的杂散场，由此间接推断了磁畴构型的信息。通过X射线衍射和透射电子显微镜的研究，建立了薄膜内部漏磁场变化与显微组织变化之间的关系：结构演化伴随着内部磁化强度的强烈变化。这种关系在随机各向异性模型的框架下得到了解释，包括温度引起的交换关联长度和饱和磁化强度的可逆变化。此外，还讨论了颗粒的总体几何特征在确定颗粒大小时所起的作用。
Micrometric, irregularly shaped Fe particles with a nanocrystalline structure have been prepared by mechanical attrition through ball-milling. Electron holography has been employed to visualize the stray field emerging from isolated Fe particles, both at 300 K and at selected temperatures T⩽1200 K, from which indirect information on the magnetic domain configuration has been inferred. By complementary x-ray diffraction and transmission electron microscopy investigations a relationship has been established between the changes of the leakage field and of the microstructure upon annealing: it indicates that the structural evolution is accompanied by strong modifications in the interior magnetization pattern. This relationship finds explanation in the framework of the random anisotropy model, including temperature-induced reversible variations in the exchange correlation length and saturation magnetization. Moreover, the role played by the overall geometrical features of the particles in the determination of ...