Neutron diffraction and magnetization measurements on CeNi4.2Mn0.8 and Y0.7Ni4.2Mn0.8

The cubic CeNi sub 4 Mn compound has been claimed to show a large spin polarization, magnetic moment and a high Curie temperature. To verify these properties we have carried out the magnetometric and neutron diffraction experiments on the nominally polycrystalline CeNi sub 4 Mn and YNi sub 4 Mn compounds. The real stoichiometry was estimated based on X ray photoemission and neutron diffraction as CeNi sub 4.2 Mn sub 0.8 and Y sub 0.7 Ni sub 4.2 Mn sub 0.8 . The magnetic properties of Y sub 0.7 Ni sub 4.2 Mn sub 0.8 have been studied with neutron diffraction to investigate the role of the rare earth in CeNi sub 4.2 Mn sub 0.8 . We have found that the samples crystallize in the hexagonal CaCu sub 5 type of structure. The deviation from the cubic structure is ascribed to the presence of a small nonstoichiometry. These structural changes are accompanied by a drop of the magnetic parameter