MAGNETIC COUPLING BETWEEN RARE-EARTH MOMENTS IN SOME ANTIFERROMAGNETIC GD COMPOUNDS

The rare earth intersublattice exchange coupling has been studied for several Gd-based antiferromagnetic compounds: GdSi, GdGe, GdSi1.67, Gd Ge1.67, GdAg2 and GdAu2 by means of the HFFP (high-field free powder) method. The values of the intersublattice coupling constants obtained by this method were compared with values derived from a mean field ana lysis of experimental values of the Neel temperature, T-N, and paramag netic Curie temperature, Theta(p). For several of the compounds invest igated a complete moment reversal from the antiparallel to the paralle l configuration could be reached in the high-field regime. The reduced saturation moment of the Gd atoms in the parallel configuration is di scussed in terms of a reduced moment contribution of the valence elect rons.