The structures and magnetic properties of FeN films prepared by the facing targets sputtering method

Abstract

The Fe nitride films were easily produced by facing targets sputtering (FTS). The structures and magnetic properties of the films depend on the reactive pressure (PN) and dc substrate biasing voltage (Vb). α-Fe, α″-Fe16N2, γ′-Fe4N, ε-Fe3N, and ζ-Fe2N as well as the amorphous FeN phase have been produced at the PN ranges of 0–8×10−3 Torr. The magnetic moment per iron atom increases with PN until PN=1.0 mTorr at which the α′-Fe16N2 phase appears with the coercive force Hc=103 A/m, susceptibility χm=161, and μS=2.85 μB. The relation between conductivity and temperature σ-T indicates that Fe nitride films resemble a semiconductor. The Curie temperature of these films is reduced with the increase of PN. Magnetic relaxation phenomena were observed in the vicinity of 540 °C.