Effects of substrate temperature and annealing on the magnetic properties of FeN films

The properties of iron nitride (FeN) thin films for high-density recording media prepared by the ion-assisted vapor deposition method have been studied as a function of substrate temperature during deposition. The coercivity shows a decrease with increasing temperature. This could be caused by the disordered growth of the columns and a decrease in the magnetic separation owing to the migration of the paramagnetic phase. Annealing tests shows that the coercivity decreases greatly following treatment above 250°C, owing to the decrease in the paramagnetic component in the FeN films. It is concluded that the shape anisotropy of the obliquely oriented columnar structure and magnetic separation effects due to the paramagnetic components that segregate along each column are the main origin of the high coercivity of FeN films