Influence of various substrate materials on the structure and magnetic properties of Fe–N thin films deposited by DC magnetron sputtering

The Fe–N films were synthesized on glass, single crystal Si (100), and NaCl (100) substrate, respectively, by DC magnetron sputtering, and the substrate temperature was optimized to obtain the single-phase γ′-Fe4N magnetic film. The structure and morphology of the samples were characterized using X-ray diffraction (XRD) and atomic force microscopy (AFM). The magnetic properties of the thin films prepared on different substrates were investigated by superconducting quantum interference device (SQUID). The results showed that substrate materials had a significant influence on the magnetic properties of single-phase γ′-Fe4N. The saturation magnetization of films on three different substrate materials had almost the same value, but the coercive force of the films was higher on single-crystal substrates than that of on the amorphous glass substrate. It was also found that the deposition temperature for obtaining single-phase γ′-Fe4N films on NaCl (100) substrate is the lowest. Furthermore, with decreasing of γ′-Fe4N grain size, the coercive force of thin films also decreased. However, the surface roughness had not resulted in much more differences in coercive force for the single-phase γ′-Fe4N thin films with the same thickness.