Magnetic and structural studies of erbium-iron-manganese-boron alloy (invited)

We report the results of neutron diffraction and magnetization measurements on powder samples of Er2(Fe,Mn)14B. We find that the unit cell expands with increased concentration of manganese as larger manganese atoms replace the smaller iron atoms within the transition metal sublattice. The preferential occupancy of transition metal sites is also affected since manganese prefers positions with larger site volumes, such as the j2, while iron prefers smaller site volumes, such as the k2. At low temperatures (4.2 K) the simple collinear moment model of the magnetic structure, valid at higher temperatures, is not sufficient to explain the existence of reflections forbidden in the space group P42/mnm. A five-sublattice model is used in which each of the two rare-earth sites splits into two distinct sublattices whose moments are oppositely canted from the direction antiparallel to the transition metal moment. The linear field dependence of the magnetization provides support for this moment configuration. Neutron diffraction analysis of the transition metal moments is compared to the compositional dependence of the magnetization