纳米FePt颗粒:MgO多层复合薄膜的外延生长、微观结构与磁性研究

Epitaxial growth micro-structure and magnetic studies of FePt nanoparticles: MgO multi-layer composite thin films

采用脉冲激光沉积法,在MgO(100)面上外延生长了FePt:MgO多层纳米复合薄膜,FePt成分为Fe48Pt52.FePt纳米颗粒周期性嵌埋于单晶MgO外延层中.原位反射式高能电子衍射分析结果表明,MgO外延层呈层状生长,而FePt纳米颗粒呈岛状生长.在整个FePt:MgO纳米复合薄膜的生长过程中,成功实现了层状-岛状生长模式的交替控制.高分辨透射电子显微镜分析结果表明,退火热处理后,结晶完整的L10-FePt纳米颗粒粒径约为5 nm,呈扁平六角形状,在MgO基底上形成逐层排列的纳米点阵.磁滞回线结果表明,退火后薄膜矫顽力增大,有序度提高,磁性增强.

The FePt：MgO multi-layer nanocomposite thin films are deposited on MgO （100） substrates by using pulsed laser deposition method. The composition of FePt is Fe48Pt52. FePt nanoparticles （NPs） are embedded in MgO epitaxial layer periodically. The results of in-situ reflection high energy electron diffraction show that MgO epitaxial layers grow into the layer-by-layer mode and FePt NPs grow into the island mode. The alternation of the two growth modes is achieved in the whole deposition process. The high resolution transmission electron microscope results show that the phase of FePt is converted from the disordered face-centered cubic structure into the ordered face-centered tetragonal L10 structure after annealing. The perfect crystalline FePt NPs （around 5 nm in diameter） are flat-hexagonal in shape and array layer by layer on MgO matrix. The M-H loop of the film shows that the ordering degree and magnetism are enhanced after annealing.