Structural and magnetic properties of L1₀-FePt/Fe exchange coupled nano-composite thin films with high energy product

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• 作者：Jiansheng Wang ; Bo Yang ; Wenli Pei ; Gaowu Qin ; Yudong Zhang ; Claude Esling ; Xiang Zhao ; Liang Zuo
• 关键词：Exchange coupling ; FePt ; High energy product ; Permanent magnets
• 刊名：Journal of Magnetism and Magnetic Materials
• 出版年：2013
• 出版时间：November, 2013
• 年：2013
• 卷：345
• 期：Complete
• 页码：165-170
• 全文大小：1942 K

文摘

Nanoparticle-FePt/Fe bilayer thin films with different Fe layer thicknesses and [nanoparticle-FePt/Fe]_n multilayer thin films with various periods were fabricated by DC magnetron sputtering. Their structures and magnetic properties (energy product and exchange coupling) were investigated by X-ray diffraction technique and vibrating sample magnetometer, respectively. The results show that coercivities of FePt/Fe bilayer films are dropped from 10.7 kOe to 0.53 kOe with increasing Fe soft magnetic layer thickness, due to the interconnecting of FePt nano-particles by Fe-rich soft magnetic phase and decreasing of the ordering degree of L1₀-FePt phase. The critical Fe layer thickness changing the annealed film from granular to continuous microstructure is about 4 nm. For multilayer [FePt/Fe]_n films, both ordering degree of L1₀-FePt phase and magnetic properties are improved with the number of layer periods. Moreover, a maximum energy products as high as 21.65 MGOe is obtained in the [FePt/Fe]₅ multilayer film. The enhancement of saturation magnetization and energy products can be ascribed to the high ordering degree of FePt phase as well as the strong exchange coupling among L1₀-FePt hard magnetic phase and Fe-rich soft magnetic phase.