Electronic and magnetic properties of cubic lave phase compounds

Band structure calculations and magnetic measurements were performed on RM2-based compounds, where R is a rare-earth or yttrium and M = Fe, Co or Ni. The exchange enhanced paramagnets as Y(CoxNi1-x)2, at T 10 K, show a T2 type dependence of magnetic susceptibilities. Above a characteristic temperature, T* , a Curie-Weiss behaviour was evidenced. The computed mean square amplitude of spin fluctuations, at high temperatures, describes well the experimentally determined effective moments. The transition of cobalt atoms from nonmagnetic to magnetic state was analysed. A small nickel moment is induced in RNi2 compounds with magnetic rare-earths. The exchange interactions influence little iron moments. The different contributions to the R5d bands polarizations are also analyzed