Magnetic properties of Fe-N/Si-N multilayer films

Fe-N/Si-N multilayer films have been deposited by an opposed-target sputtering apparatus, and their structure and magnetic properties were investigated in detail. The multilayer films deposited at a proper nitrogen gas flow rate, R_N2, have amorphous crystal structure and show excellent soft magnetic properties (coercive force of 0.6 Oe). The nitrogen atoms in the Fe-N layer of the film can move easily to the Si-N layer at temperatures below 200°C if the Si-N layer contains a small amount of nitrogen. The interdiffusion of the metal atoms between the Fe-N layer and the Si-N layer can occur in the film by annealing at a temperature above 400°C. In the film with nitrogen content above 20 at.%, the nitrogen content in the Fe-N layer changes very little even if the annealing is performed at a temperature above 600°C and its layered structure can be kept stable. These results suggest that the Si-N layer can be used to realize multilayer films with good thermal stability. Annealing at a temperature above 400°C can lead to a growth of crystallites in the film, which deteriorates the soft magnetic properties of these films