L1_0-FePt合金单层磁性薄膜的微磁学模拟

Micromagnetic modeling of L1-0-ordered FePt magnetic thin films

具有四方结构的L10-FePt合金因其具有高磁晶各向异性和良好的化学稳定性而成为超高密度薄膜磁记录介质的最佳选择.对实验制备得到的磁性能良好的垂直取向L10-FePt合金单层膜进行了微磁学分析.在传统微磁学模型的基础上,根据晶体的对称性,引入了四角磁晶各向异性能密度的唯象表达形式;又依据薄膜生长过程中晶格对称性的破坏,考虑了薄膜面内的应力,并引入了磁弹性能.以四角磁晶各向异性能和磁弹性能为重点,对L10-FePt合金单层膜的磁滞回线进行了详细的分析,并且用微磁学方法确定了薄膜面内应力的大小.

The L10-ordered FePt films are promising materials for ultra high density magnetic recording media due to their high magnetic anisotropies. In this work, the L10-ordered FePt thin films are prepared by magnetron sputtering on CrW underlayer. A three-dimensional micromagnetic model, based on the symmetry of the L10 phase, is set up for FePt perpendicular media. According to the mismatch between the underlayer and FePt magnetic layer, a residual tensile stress is applied in the film plane. The simulated M-H loops accord well with the experimental results. The tetragonal crystalline anisotropy, especially high in-plane anisotropy, could enlarge the in-plane coercivity. The simulated perpendicular and longitudinal loops each have an open up in the tail, which is mainly due to the magnetostriction of the L10 phase.