Investigation on magnetic properties and narrow domain wall of Tb2Fe17-xSix single crystals

The magnetic properties and narrow domain are investigated. The substitution of silicon for iron leads to the reduction of the lattice parameters, and the significant increase of the Curie temperature from 413 K to 526 K, The mean field analysis show that the Fe-Fe exchange interaction is much strengthened while the Tb-Fe one is slightly weakened by the introduction of silicon. The anisotropy constants up to the sixth order are calculated by fitting the magnetization process of the samples with the different silicon contents at 1.5 K under the field up to 5.2 x 10(6) A/m. At low temperature, the intrinsic coercivity has been observed. The domain wall energy and wall thickness were calculated by counting in three anisotropy constants up to the sixth order and the results indicated that the coercivity is caused by the typical narrow domain wall pinning-dominated process. The domain wall energy and wall thickness were also calculated based on the Egami thermal-activation model and the empirical relationship for H-c(T). The mechanism for the intrinsic coercivity was discussed.