稀土永磁薄膜材料

RARE EARTH PERMANENT MAGNETIC FILMS

简要地介绍在纳米复合稀土永磁薄膜材料、各向异性稀土永磁薄膜材料方面的进展。在纳米复合稀土永磁薄膜材料中实现磁性交换耦合和剩磁增强效应,系统地研究了其结构与磁性的关系。制备成功高磁能积的各向异性稀土永磁薄膜材料,比较了Ti或Mo缓冲层对Nd-Fe-B薄膜的表面形貌、磁畴结构和磁性能的影响。发现薄膜的表面形貌强烈地依赖于缓冲层的厚度。由于它极大地影响薄膜的成分,溅射速率被证明是控制薄膜的显微结构、表面形貌和磁性能的一个重要因素。在微磁学模型的基础上,通过分析从5到300 K的矫顽力温度依赖关系。研究了各向异性Pr-Fe-B薄膜的矫顽力机制。在晶粒表面,由于磁各向异性的降低和局域退磁场的提高导致的反转畴的形核被确定为控制各向异性Pr-Fe-B薄膜的磁化反转过程的首要机制。

Recent progress in nanocomposited rare-earth permanent magnetic films and anisotropic rare-earth permanent magnetic films was briefly reviewed. The exchange coupling and remanence enhancement were realized in nanocomposited rare-earth permanent magnetic films fabricated by sputtering. The relations between structure and magnetic properties of nanocomposited permanent magnetic films were studied. On the other hand, anisotropic Nd-Fe-B permanent magnetic films with c-axis texture and high maximum energy products were fabricated by sputtering. The influence of Ti or Mo buffer layer thickness and substrate temperature on the surface morphology, the domain structure and the magnetic properties was investigated and compared for the Nd-Fe-B films. It was found that the morphology of the surface strongly depended on the thickness of the buffer layer. The microstructure, the surface morphology and magnetic properties of Nd-Fe-B thin films were strongly dependent on the deposition rate, which was mainly due to the variation of chemical compositions in the thin films. The coercivity mechanism of the anisotropic Pr-Fe-B films was studied by analyzing the temperature dependence of coercivity from 5 to 300 K, based on the micromagnetic model. Nucleation of reversed domains, taking place preferentially at the grain surface where the magnetic anisotropy was reduced and the local demagnetization field was the highest, was determined to be the leading mechanism in controlling the magnetization reversal processes of the anisotropic Pr-Fe-B films.