MEAN-FIELD THEORIES OF SPIN-CLUSTER STATES IN CUO2 PLANES

The appearance of spin polarized states (magnetic polarons) in hole do ped CuO2 layers of the high-T-c systems is investigated. Starting from a three-band Hubbard model which is treated in the Hartree-Fock and t he slave-boson saddle-point approximation, respectively, the spin dist urbed structure around a single hole is studied in detail. The change of the spin cluster polarization towards metalization in dependence of the hole concentration is discussed. Furtheron we investigate the com petition between the formation of these self-localized one-particle st ates with the occurence of correlated two-particle singlet states.