Phase separation based on a U(1) slave-boson functional integral approach to the t-J model

Based on the U(1) slave-boson functional integral approach to the t-J model Hamiltonian, we investigate the phase diagram of phase separation for the hole-doped two-dimensional system of antiferromagnets. We discuss the phase separation (into a hole-rich and a hole-free phase) as a function of J/t w here J is the Heisenberg (antiferromagnetic) coupling constant and t the ho pping energy. For the physically interesting region of relatively small Hei senberg coupling, 0<J/t<0.2, we find that the phase separation occurs in a region of hole doping concentration below x(c)similar to0.1 and that in the same region the critical hole doping concentrations remain robust with nea rest-neighbor hole-hole repulsive interactions. On the other hand, in the r egion of larger J/t the phase separation boundary is found to be highly sen sitive to the variation of the repulsive hole-hole interactions. In agreeme nt with other studies, we find that the phase separation occurs at a critic al value of J, approximate to3.4t corresponding to the critical hole concen tration x(c)=1.