ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The effect of carbon diffusion from CH4 gas into coarse Sm2Fe17 powder on the magnetic domain structure (MDS) was studied at room temperature by means of the magneto-optical polar Kerr effect. The diffusion occurs initially along preferential paths and then through the bulk. A gradual variation in the MDS through incompletely carburized grains was observed, which reflects local changes in spontaneous magnetization and magnetic anisotropy. This suggests the existence of smooth "bathtublike'' carbon concentration profiles. An acceleration of the carburization process caused by cracking of grains during the diffusion was observed. The diffusivity R of carbon in Sm2Fe17 at 450 °C was estimated to be 2.5×10−16 m2/s. For Sm2Fe17C2.2 the domain-wall energy density is γ=3.1×10−2 J/m2, the domain-wall thickness δ=3.3 nm, the single-domain particle size Dc≈0.3 μm, and the exchange constant A=8.1×10−12 J/m.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.358177
