Magnetic structures of MFe4+delta Al8-delta (M = Lu,Y) - art. no. 054410

The magnetic structure of nonstoichiometric LuFe4+deltaAl8-delta and YFe4+d eltaAl8-delta compounds with a small Fe excess (delta similar to0.40) was i nvestigated by Mossbauer spectroscopy, magnetization measurements, and both polarized and unpolarized neutron-scattering experiments on single crystal s. The small excess of Fe atoms substitute Al at the 8j positions and have a pronounced effect on the magnetic properties. The Neel temperature decrea ses from similar to 190 to 100 K and the magnetic ordering changes from the cycloid modulation found in the stoichiometric compounds to an amplitude m odulated wave with a much shorter period.