Evolution of hole and magnon spectra of the two-dimensional<i>t</i>-<i>J</i>model with doping

Abstract

Hole and magnon spectral functions of the two-dimensional t-J model are self-consistently calculated for hole concentrations x\ensuremath{\lesssim}0.3. 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 \ensuremath{\mu} into a sharp maximum of the density of states. With increasing x the maximum moves together with \ensuremath{\mu} up to x\ensuremath{\approxeq}0.15 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 x\ensuremath{\approxeq}0.02, 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 x\ensuremath{\gtrsim}0.05.