Magnetism of Nd–Fe films as a model of grain boundary phase in Nd–Fe–B permanent magnets

To clarify the magnetism of an amorphous grain boundary (GB) phase in Nd–Fe–B sintered magnets, the magnetic properties of Nd100−xFex films with various compositions have been investigated both experimentally and theoretically. The model films exhibit ferromagnetism at room temperature when the Nd content is lower than 70 at. %. First-principles calculations indicate ferromagnetism in fcc Nd–Fe alloys for x < 70, which supports recent experimental works on the intergrain exchange coupling of Nd–Fe–B sintered magnets.