Band structure, magnetic fluctuations, and quasiparticle nature of the two-dimensional three-band Hubbard model

A single hole doped into the CuO2 plane of a high-Tc superconductor is studied via exact calculations of the three-band Hubbard model (large-U limit) on a 4×4 periodic cluster. The quasiparticle band has its bottom at k=(π/2,π/2) and disperses strongly towards Γ and X with a dispersion 1.7Jdd=0.22 eV. The quasiparticle has a nearly isotropic effective mass (∼4me) and the dressing effects are well localized (∼8 ) with characteristic features of both the three-spin polaron and the Zhang-Rice singlet (although solutions of the t-J model are substantially different).