EVOLUTION OF HOLE AND MAGNON SPECTRA OF THE 2-DIMENSIONAL T-J MODEL WITH DOPING

Hole and magnon spectral functions of the two-dimensional t-J model are self-consistently calculated for hole concentrations x0.3. The employed system of Dyson's equations was obtained with the use of the Born and spin-wave approximations. It is shown that near x=0.05 the hole spectrum is changed drastically acquiring features of a weakly correlated spectrum. This change is accompanied by a substantial decrease of the carrier effective mass and by entering the chemical potential μ into a sharp maximum of the density of states. With increasing x the maximum moves together with μ up to x0.15 and then lags behind. This concentration is also distinguished by the facts that the Fermi surface becomes a simply connected surface and overdamped magnons, which appear at x0.02, occupy the widest region in k space. Besides, here usual magnons have the smallest limiting frequency which is approximately three times smaller than the initial one. Significant deviations from the normal Fermi liquid, which partly resemble marginal Fermi liquid, are observed for x0.05. © 1994 The American Physical Society.