EFFECT OF COMPOSITION ON THE MAGNETIC BEHAVIOUR OF Gd2X COMPOUND

The eigenvalues of the isotropic magnetic interaction system extraction from Internal Field Approximation (IFA) q e computed. on the basis of RKKY for the complicated magnetic behaviour of Gd, X system X= (Au , Pt , Al , In ) as well as Gd. From the strength and slope of eigenvalue curves in different ranges of interaction the strength and sharpness of the magnetic transition can be suggested. It is shown that the values of the first transition temperature "T " as ferromagnetic ordering "F.M", as well as its sharpness in the short-range interaction "R ", includes at least two atomic layers, this being in agreement with reported experimental results. In the long-range interaction, the second transition is predicted to be of the antiferromagnetic order "AF.M" for Gd ,Al and Gd , In. It becomes impossible to see the second transition for Gd Pt and Gd Au as interaction range is increased. For pure metallic "Gd", however, the transition is shown to be of the helicoidal type in the range of " 12- 17" A?, where all of these results correspond to experimental observations