Magnetization processes caused by iron substitution in cubic laves phases

The magnetic properties of cubic Laves phases RE(Fe, M)₂, M = Al, Co, Rh are discussed. Pauli-paramagnetism is obtained for all three YM₂ compounds. The appearance of a percolation limit for the onset of long-range ferromagnetic order which depends strongly on the matrix susceptibility is characteristic for all investigated series Y (Fe, M)₂. Mictomagnetic behaviour can be deduced from magnetic, Mössbauer- and neutron depolarization measurements below the percolation limit. A Co moment of approximately 1 μ_B is induced in RECo₂ compounds, RE = Gd, Dy, Ho. On the contrary Rh has no magnetic moment in these compounds. Within the RE(Fe, Co)₂ series a Co moment is induced by both the RE and Fe atoms, whereas within RE(Fe, Rh)₂ the Rh atoms will only be influenced by the substituted Fe. In all compounds the spin of the heavy RE atoms couples antiparallel to the spin of the transition metal atoms. Local environment effects are important for all Fe containing series whereas the properties of RECo₂ compounds evidence itinerant electron metamagnetism.