Granular films of Fe/Sm–Co magnetic nanocomposites through spin-assisted layer-by-layer deposition

Abstract

Films of Fe/Sm–Co magnetic nanocomposites were successfully synthesized by means of spin-assisted layer-by-layer deposition. The Fe-layer thickness was varied by controlling the spinning speeds and its effect on the structural and magnetic properties of Fe(t Fe)/Sm–Co(250 nm) films with t Fe = 15 and 30 nm was investigated. Energy-dispersive X-ray analysis confirmed the presence of Sm, Co, and Fe in the samples, which suggests complete decomposition of the precursor films after reductive annealing. Atomic force microscopy examinations revealed the formation of spherical grains in the Sm–Co layer and the estimated mean grain size values were slightly lower for t Fe = 15 nm (34 ± 6.3 nm); when compared to those obtained for t Fe = 30 nm (48 ± 8.4 nm). Irrespective of t Fe, X-ray diffraction studies showed the crystallization of Sm(Co,Fe)7-phase in both the films after their reduction at 500 °C and this metastable phase was transformed into SmCo5 and Sm2Co17-phases on annealing at 600 °C. The occurrence of these two phases was further confirmed by thermomagnetic measurements in terms of distinguished magnetic transitions at ~723 and ~905 °C, respectively. Room temperature magnetic measurements by superconducting quantum interference device, demonstrated the influence of t Fe on the hard magnetic behavior of the films. A good combination of high coercivity (6.2 kOe), high remanence ratio (0.73), and magnetization (3.35 memu) was obtained with t Fe = 15 nm. The results of our study suggest that the simple spin coating process can be applied efficiently to produce thick magnetic films of Fe/Sm–Co for possible applications in magnetic micro-electro-mechanical system devices.