Effect of thermal annealing on nitrogen implanted epitaxial Fe films

Nitridated iron is a promising material for potential applications in permanent magnets. Recent work on stabilization of nitridated iron in a foil form through nitrogen ion implantation and annealing motivates to study effect of thermal annealing on the surface of nitrogen-implanted iron. In this work, we show effect of annealing on chemical state and magnetism of nitrogen implanted epitaxial iron films. It is observed that nitrogen in the lattices only stays at the lower temperatures than 450 degrees C. In addition, significant reduction and lattice modification are taken placed, when the film is annealed at 450 degrees C. The increases of saturation magnetization and coercivity, where it is annealed at 450 degrees C, are likely to be triggered by reduction of oxygen contents at the surface and thinning of Fe2O3.