Influence of substrate temperature on structure, microstructure and magnetic properties of sputtered Fe–Ga thin films

• Columnar growth of nano-crystalline grains of A2 phase observed in the films.
• Coercivity is found to be influenced by grain size and surface roughness of the films.
• A very low coercivity (~2 Oe) and a large magnetostriction (~200 µ-strains) has been achieved in films grown at 450 °C which are very important and desirable properties for a magnetostrictive thin film.

This paper reports the structure, microstructure and magnetic properties of Fe–Ga thin films deposited using DC magnetron sputtering technique on Si(100) substrate kept at different temperatures. Structural studies employing X-ray diffraction and TEM revealed the presence of only disordered A2 phase in the film. Columnar growth of nanocrystalline grains from the substrate was observed in the film deposited at room temperature. With increase in substrate temperature the grain size as well as surface roughness was found to increase. The magnetization of the films deposited at higher substrate temperatures were found to saturate at lower magnetic field as compared to the room temperature deposited film. Coercivity was found to decrease with increasing substrate temperature upto a minimum value of ~2 Oe for the film deposited at 450 °C and with further increase in substrate temperature it was found to increase. A maximum magnetostriction of 200 µ-strains was also observed for the film deposited at 450 °C.