A STUDY OF MAGNETIC COUPLING IN GDT2SI2 COMPOUNDS (T = TRANSITION-METAL)

The magnetic coupling in the GdT2Si2 (T=transition metal) antiferromag netic compounds is studied by means of DC susceptibility and high-fiel d free-powder (HFFP) measurements. In most compounds, the experimental results can be described in the framework of a two-sublattice model w ithout anisotropy. From this analysis, an intrasublattice exchange cou pling constant, n(11), and an intersublattice exchange coupling consta nt, n(12), are obtained. The exchange couplings are discussed in terms of the change of the lattice parameters, the volume V and the filling of the transition metal electron band. The apparently reduced value o f the moment per Gd atom in the forced ferromagnetic configuration is attributed to a reduction of the on-site 5d-moment and a possible nega tive polarisation of the other non-4f electrons. (C) 1997 Elsevier Sci ence S.A.