Magnetic and structural properties of Fe$_{87}$Pt$_{13}$–Al$_{2}$O$_{3}$ composite thin films synthesized by solid-state reactions

The structural and magnetic properties of Fe$_{87}$Pt$_{13}$ films synthesized by solid-state reactions and Fe$_{87}$Pt$_{13}$–Al$_{2}$O$_{3}$ composite films fabricated by aluminothermy are investigated. It is shown that the synthesized samples of both types are characterized by the rotational magnetic anisotropy, when the easy magnetization axis in the film plane can be set by a magnetic field. It is established that the value of rotational magnetic anisotropy in the Fe$_{87}$Pt$_{13}$–Al$_{2}$O$_{3}$ composite films is higher than in the Fe$_{87}$Pt$_{13}$ samples by an order of magnitude. The rotational magnetic anisotropy is assumed to be caused by the exchange coupling of the L1$_{0}$–FePt phase with the L1$_{2}$–Fe$_{3}$Pt phase in the Fe$_{87}$Pt$_{13}$ films and magnetic iron oxides in the Fe$_{87}$Pt$_{13}$–Al$_{2}$O$_{3}$ samples.