Rietveld refinement of powder neutron diffraction data, combined with group theory considerations, is used to determine the magnetic structures of the binary metal dicyanamide, (formula presented) where (formula presented) Co, Fe, Mn, (formula presented) and (formula presented) Compounds with (formula presented) or Fe show a canted antiferromagnetic arrangement of spin oriented in the ab crystallographic plane, with antiparallel components of the two sublattices along the a axis and parallel along the b axis. Symmetry considerations forbid an additional moment, whether compensated or not, to be present along the c axis. The compounds with fewer unpaired electrons (Co and Ni) are ferromagnets, with all moments oriented along the c axis. The mixed composition of (formula presented) displays the same collinear ferromagnetic structure as its parent compounds. However, the composition with (formula presented) whose parent compounds show different magnetic behavior, does not exhibit long-range magnetic ordering down to 1.7 K. Magnetostriction was observed for the ferromagnets for which we investigated the variable temperature powder neutron diffraction. The cobalt-rich compounds show more pronounced effects, consistent with their increasing magnetocrystalline anisotropy.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2003 Apr 7|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics