INTERPLAY BETWEEN THE KONDO EFFECT AND THE RUDERMAN-KITTEL-KASUGA-YOSIDA INTERACTION IN THE 2-IMPURITY MODEL

The applicability of the Kondo Hamiltonian as a microscopic model for some Ce-based magnetic alloys such as CexLa1-xPb3 and CexLa1-xCu6 wher e the specific heat and the magnetic suceptibility increase linearly i n x for a wide range of x is discussed. The results of the phenomenolo gical analysis of formulating the magnetic impurities as scattering ce ntres would suggest that the impurities in these alloys are near the u nitary limit. On the other hand, a perturbation analysis for the two-i mpurity Kondo model indicates that the zero-temperature magnetic sucep tibility for two impurity spins differs significantly from those of th e independent impurities owing to the Ruderman-Kittel-Kasuga-Yosida (R KKY) interaction. This suggests that the Kondo Hamiltonian may not be appropriate for these alloys even in the dilute limit. The meaning of the RKKY interaction at low temperatures is also discussed.