Structure and magnetic properties of Y(Co 1− xM x) 5 compounds

Abstract

The structures of the pseudobinary Y(Co 1− x M x ) 5 compounds (M ≡ Ni, Cu, Al, Ti, V, Cr, Mn, Fe) and the magnetic properties of the Y(Co 1− x Ni x ) 5 compounds in particular were investigated. It was found that a large homogeneous single-phase region with a CaCu 5-type structure forms when M is nickel or copper. The homogeneous range becomes restricted when M is a metal other than nickel or copper. The experimental results are critically examined in terms of the atomic size effect and the electron concentration factors. It is believed that continuous substitution in the Y(Co 1− x Ni x x ) 5 system is primarily due to the smaller atomic size and weaker magnetic moment of the nickel atoms. There are strong indications that the nickel atoms preferentially occupy the 2c sites of the cobalt atoms. The composition dependence of the lattice constants and the interatomic distances can be satisfactorily accounted for by the nickel atoms occupying the 2c rather than the 3g sites in the hexagonal CaCu 5-type lattice. The composition dependence of the Curie temperatures and the temperature dependence of the magnetization of Y(Co 1− x Ni x ) 5 compounds were studied. The intrinsic coercive force I H c at cryogenic temperatures is discussed in terms of the localized moment model. The composition dependence of I H c was analysed in detail by using the moment distribution function and other intrinsic parameters.