EFFECT OF RARE-EARTH OVERLAYERS ON THE COERCIVITY IN Nd-Fe-B FILMS

摘要

We fabricated a model interface system, which consists of the Nd_2Fe_(14)B layer with the rare-earth (R = Dy) overlayers in order to study the relationship between microstructure near the interface and the coercivity. Nd_2Fe_(14)B particles with the nearly random orientation of c-axis were prepared by using high vacuum magnetron sputtering system. We introduced high-melting-point bcc-Ta, as a buffer layer on the heat-resistant glass substrates. When the substrate temperature during the deposition of the 1 μm thick Nd-Fe-B layer was 700°C, the demagnetization curve of this film without rare-earth overlayers exhibited a coercivity value of 3.3 kOe. On the other hand, experiments on the post-annealed Nd-Fe-B films with the Dy overlayer showed a significant increase in H_c of up to 17 kOe.