A two-dimensional model for the coercivity mechanism of Sm&!o,Fe,Cu,Zr)~, magnets is proposed. The high coercivities of fully heat-treated magnets (> 20 W c m ) result from pinning sites which are formed by the intersections of the Zr-rich platelet phase (Z-phase) and the Cu-rich SmCos (US) boundary phase. The pinning strength of this site is assumed to be a result of the large difference between the domain wall energies of the 115 phase and the Z-phase. The domain wall energies of almost single phase samples of the Zphase have been determined by magnetic measurements and by quantitative analysis of domain patterns. The small domain wall energy of the Z-phase of 4 -11 mJ/m2 supports the presented model.

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A magnetic and Mössbauer spectroscopy study of nonoriented and magnetically oriented samples of Nd6Fe13Sn was performed. At 4.2 K a metamagnetic transition takes place in a field of 7.1 T. Strong evidence for antiferromagnetic spin arrangements in the iron magnetic sublattice and antiferromagnetism of the Nd moments with only a small contribution to the net magnetization in fields up to 14 T was found.