INVESTIGATION OF THE DOMAIN-STRUCTURE OF SM2FE17NX INTERMETALLIC NITRIDES

In the present work the change of the easy magnetization direction fro m easy plane to easy axis of the primary compound Sm2Fe17 by absorbing nitrogen is directly observed by the domain pattern. The intrinsic ma gnetic parameters of nitrided SM2Fe17Nx such as domain wall energy gam ma, average exchange constant A. domain wall width delta(B), as well a s the critical diameter of single domain particles D(c) are estimated. The domain behavior of Sm2Fe17Nx under the applied external field is also investigated. Our results indicate that the nuclei initially occu rring in the bulk of the grain are weakly pinned and that the coercivi ty of the material is dominated by the nucleation occurring at the sur face of the grain, which is relative larger than the pinning field wit hin the grain. In the Sm2Fe17N2.15 compound, a three-dimensional domai n pattern is observed, which directly gives an experimental support of Goodenough's assumption that the walls are slabs in the main body and zigzag undulatory walls with a decreasing amplitude of undulations wi th increasing distance from the surface.