Chang, Z (reprint author), CCAST, World Lab, POB 8730, Beijing 100080, Peoples R China.
Within the framework of the supergroup theory and by making use of the general Holstein-Primakoff transformation, we set up an infinite hierarchy of equations of motion in the Green's functions for the t-J model. A physical criterion involving self-consistency of the decoupling is presented. A Green's function method for the t-J model, approximately valid through the entire temperature range, is given for low doping case. At low temperatures, the sublattice magnetization is in good agreement with the neutron scattering experiments in the high-temperature superconductors. The Neel temperatures and features at the antiferromagnetic-metalic phase transition region are obtained by taking into account the doping effect. (C) 1999 Academic Press.