| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1800038 | Journal of Magnetism and Magnetic Materials | 2013 | 6 Pages |
•The microstructure evolution of FePt/Fe bilayer thin films and decreasing of ordering degree with the increasing of the Fe layer thickness.•Enhancement of saturation magnetization and energy products of multilayer [FePt/Fe]n films with increasing of the number of layer periods were observed.•A maximum energy products as high as 21.65 MGOe is obtained in the [FePt/Fe]5 multilayer film.•We systemically investigated the exchange coupling of FePt/Fe thin films by ΔM technique.
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.
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