Fabrication and characterization of sputtered Ni₂MnGa thin films

Ni₂MnGa bulk specimen has a Heusler-type crystal structure and is ferromagnetic. The cubic structure transforms to a tetragonal structure through the martensitic transformation during cooling. In this study, Ni₂MnGa thin films were deposited on a PVA substrate by the sputtering method using a high frequency magnetron sputtering apparatus. The thickness of the film was 5 μm. The Heusler type cubic crystal structure of the film, which was annealed at 1073 K for 3.6 ks, changed to a tetragonal structure by martensitic transformation during cooling. Temperature dependence of magnetization was observed under the external magnetic field which was applied parallel and perpendicular to the film. The magnetization was saturated under the external magnetic field of 400 kA/m applied parallel to the film while the saturation magnetization was not observed under the external magnetic field applied perpendicular to the film.