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, GdGe1.67, 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 analysis of experimental values of the Neel temperature, T-N, and paramagnetic Curie temperature, Theta(p). For several of the compounds investigated a complete moment reversal from the antiparallel to the parallel configuration could be reached in the high-field regime. The reduced saturation moment of the Gd atoms in the parallel configuration is discussed in terms of a reduced moment contribution of the valence electrons.