Phase evolution and magnetic properties of DC sputtered Fe-Ga (Galfenol) thin films with growth temperatures

Abstract

We report on the evolution of phases, morphology and magnetic properties of DC magnetron sputtered FeGa thin films with the different growth temperatures: room temperature, 100 °C, 200 °C, and 300 °C. These films were grown on Si substrate and were analysed for their morphological, structural and magnetic properties. The X-ray diffraction analysis reveals that the films are nanocrystalline and improve their crystallinity as the growth temperature increases from room temperature to 300 °C. Scanning electron microscopy images indicate grain growth and the morphology changes from spherical to platelets with increase in substrate temperatures. The films deposited at room temperature and 100 °C show very low magnetization and coercivity. On increasing the substrate temperature to 200 °C, it is observed that the M-H curves are isotropic with the films not attaining saturation. At 300 °C, there is substantial increase in coercivity and magnetization observed due to the larger grains present in the films. Magnetic properties also depend on in-plane (463 G, 46.557 emu/cc) and out-of-plane (860 G, 42.774 emu/cc) orientations with small anisotropy. Such an increase in magnetic properties is attributed to increase in grain size and change in morphology.