Dependence of the Fe anisotropy on the Dy concentration in the DyxFe6Sn6 (0.3 < x < 1) compounds

Mössbauer spectroscopy and magnetization measurements were performed on DyFe6Sn6, crystallizing in a superstructure of the HfFe6Ge6-type, Cmcm space-group, and DyxFe6Sn6 (x = 0.3, 0.5), defect isotypes of the SmMn6Sn6-type of structure, P6/mmm space-group. In DyFe6Sn6 the Fe magnetic moments, μFe, are parallel to the hexagonal c-axis. With lower Dy content however a fraction of μFe was found to be along a direction close to or in the ab-plane. This fraction of deviating μFe which is zero for Dy0.5Fe6Sn6 and 8% for Dy0.3Fe6Sn6 at 10 K increases with temperature up to 15 and 87% at 295 K, respectively. Magnetization data is consistent with a ferromagnetic-like order of the Dy sublattice below 11 and 6 K in DyFe6Sn6 and Dy0.5Fe6Sn6. In Dy0.3Fe6Sn6 no evidence was found of the ordering of the Dy sublattice down to 1.7 K.