Synthesis and magnetic properties of nanocolumnar nickel films deposited in argon-nitrogen atmosphere

Ferromagnetic nickel films with a structure comprising nanocolumns grown perpendicular to a substrate have been obtained by magnetron sputtering of a nickel target in argon atmosphere containing 2 vol % nitrogen. Measurements of X-ray diffraction and investigation of magnetic properties showed that the obtained films consist of a solid solution of nitrogen in nickel. The saturation magnetization of the films is 1.5–2 times smaller and their Curie temperature is 30 K lower than the corresponding values for pure nickel. The film material exhibits a dimensional effect: as the grain size decreases below 10 nm, the magnetization sharply drops; at a grain size of 0.5 nm, the film possesses no magnetic order.