Nitriding studies of aligned high anisotropy ThMn12-type NdFe11Co1-yMoyN film samples (abstract)

Highly aligned film samples of ThMn12-type NdFe12-y-zCoyMoz, y+z∼1, have been directly crystallized onto heated substrates by rf sputtering. The deposited films have then been nitrided at different nitriding pressures and temperatures to determine the optimum conditions to maximize the coercivity. The films have generally been (002) textured so that the easy axis of magnetization of the nitrided films is perpendicular to the film surface. For low Co concentrations it has been possible to enhance the saturation flux densities, the coercivity, and the anisotropy field of the nitrided samples. Maximum room temperature coercivities and anisotropies of 11.3 and 145 kOe were obtained for a ThMn12-type Nd8.9Fe80.3Co6.0Mo4.8N (002) textured film sample. At lower temperatures the coercivity and anisotropy rose smoothly to 29.5 and ∼200 kOe respectively by 10 K. Based on nitriding studies on similar films, all nitride sites should be occupied at ∼1 N per ThMn12 formula unit for the high coercivity films. Previously NdFe11Co0.5Mo0.5N films were reported with a room temperature BHmax=46.3 MGOe at 293 K and 59.6 MGOe at 10 K. In general, films that have been made to exhibit a gradient in any one component have exhibited lower energy products due to either a reduced coercivity or to shouldered hysteresis loops