KONDO-LATTICE - KONDO-EFFECT

The periodic s-d-model is investigated by Green function methods. We find that the ln T-divergence appearing in third order perturbation theory for the electron selfenergy is smoothed out but still shows up in a characteristic decrease (exchange coupling γ<0) or increase (γ>0) of lifetime of electrons at the fermi level as T→0 and a corresponding structure in the specific heat. However, in contrast to the single impurity case, the corresponding characteristic temperature does not vary like exp[-1/|γ|] but always is of order γ2. From a mean field theory of the model, one finds a critical temperature for a transition into a magnetically ordered state Tc0 which varies precisely like γ2. Thus an interesting competition between Kondo-effect and long-range magnetic order can be expected in this model. © 1979 Springer-Verlag.