MAGNETIC-PROPERTIES OF GD3CO11-XNIXB4 COMPOUNDS

Gd3Co11-xNixB4 compounds, with x less than or equal to 6, were investi gated by X-ny diffraction and magnetic measurements. The structural re sults show anisotropic variations of the lattice constants and a thres hold Ni content is observed, x approximate to 3, in the composition de pendence of the asymmetry parameter. The Curie temperatures and mean c obalt moments decrease as an effect of the cobalt substitution. The Gd -Co intersublattice exchange coupling estimated in the molecular field approximation shows a small composition dependence. Analyses of the e xperimental magnetic data obtained at saturation as well as in the par amagnetic temperature ranges indicate an increasing degree of itinerac y of cobalt magnetic moments as the nickel content increases. Based on previous results for the values of local cobalt moments in R(n+1)Co(3 n+5)B(2u) compounds, a preferential distribution of Ni at the Co latti ce sites is suggested.