EFFECTS OF SPIN FLUCTUATIONS IN THE T-J MODEL

Recent experiments on the Fermi surface and electronic structure of th e cuprate-superconductors showed the importance of short-range antifer romagnetic correlations for the physics in these systems. Theoreticall y, features like shadow bands were predicted and calculated mainly for the Hubbard model. In our approach we calculate an approximate self-e nergy of the t-J model. Solving the U = infinity Hubbard model in the dynamical mean field theory (DMFT) yields a self-energy that contains most of the local correlations as a starting point. Effects of the nea rest-neighbor spin interaction J are then included in a heuristical ma nner. Formally like in J-perturbation theory all ring diagrams, with t he single bubble assumed to be purely local, are summed to get a corre ction to the DMFT-self-energy. This procedure causes new bands and can furnish strong deformation of quasi-particle bands.