Preparation and magnetic properties of Mn4N films by reactive facing targets sputtering

Abstract

Ferrimagnetic Mn4N films have been successfully prepared at low process temperatures using the facing targets sputtering apparatus. The mixture gas of Ar and N2 with the ratio of N2 in pressure to total gas RN2 of 10% was optimal as the reactive working gas for depositing Mn4N films, since the deposition at excessive RN2 tended to cause the formation of Mn3N2 crystallites. In fact, they appeared in films deposited at RN2 higher than 30%. The film deposited at the substrate temperature Ts of 200 °C exhibited saturation magnetization 4πMs of about 300 G. The films prepared at Ts of 350 °C exhibited 4πMs and an in-plane coercivity Hc∥ of 450 G and 300 Oe, respectively. The films annealed at 400 °C in vacuum furnace exhibited 4πMs larger than about 510 G. However, the film annealed at temperature above 500 °C exhibited 4πMs smaller than 80 G.