Magnetic properties and structure of Mn 4N films on glass substrates

Abstract

Ferrimagnetic Mn 4N films were deposited in situ on glass substrates, by d.c. reactive magnetron sputtering from a sintered Mn target. An Mn 4N ordered structure was obtained at a substrate temperature of 150–250 °C and gas pressure of 3–8 m Torr (flow rate ratio Ar:N 2 = 2:1), without any further annealing. Perpendicular magnetic anisotropy exists in these films, resulting in a larger coercivity (1150–2300 Oe) measured perpendicular to the film plane than that parallel (650–1550 Oe). The coercivity in either direction decreases with increasing substrate temperature, while it increases with increasing gas pressure. The saturation flux density of the films is 120–610 G, increasing with increasing substrate temperatures. The resulting perpendicular magnetic anisotropy is attributed to the ordering in the crystal structure, from the stress-induced anisotropy and from the shape anisotropy.