Magnetostrictive properties and microstructure of thermally annealed Sm–Fe thin films

Polycrystalline Sm–Fe thin films were fabricated by annealing sputter-deposited Sm–Fe thin films. Although the annealing of the as-deposited Sm–Fe film tends to precipitate Fe grains, leading to a non-uniform microstructure and low magnetostriction coefficient, the thermal annealing performed in multiple steps produced a relatively large fraction of SmFe2 with uniform grain size. The Sm–Fe thin film annealed at 400, 500, and 600 °C for 1 h at each step produced the highest magnetostriction coefficient in this study; −57 ppm at an applied field of 2.5 kOe.