POLARON-TYPE TRANSFORMATIONS OF THE T-T'-J MODEL

The t-t'-J model at nearly half-filling is used to study the motion of holes in a two-dimensional square lattice with an antiferromagnetic o rder. The spin-charge separation concept is used and the t-J Hamiltoni an is exactly mapped into the tenser-product space of holons and spin states with an exact elimination of redundant degrees of freedom. The linear spin wave approximation is used. The canonical transformation o f the polaron theory is used to finally cast the Hamiltonian of the sy stem in the form describing the interacting holon-magnon system. One m agnon scattering processes are considered and the holon Green function is calculated in the self-consistent-Born-approximation. The equation for the self-energy is solved numerically. From the lowest energy pea k of the spectral function the energies of quasi-particles, i.e., holo ns heavily dressed in magnons, are calculated. (C) 1998 Elsevier Scien ce B.V.