A RENORMALIZATION-GROUP STUDY OF THE T-J MODEL

The t-J model has been proposed to describe the physics of copper oxid e planes in high-temperature superconductors. A real-space quantum ren ormalization-group method is developed in order to study the t-J Hamil tonian in a square lattice. The zero-temperature phase diagram is anal ysed for electron concentrations near the half-filled band and ratio J /t. A critical line is found that separates two distinct regions: one of a gas of holes in an antiferromagnetic background, and the other co nsisting of a phase in which holes segregate into a hole-rich and a pu re antiferromagnetic region, as demonstrated by chemical-potential eig envalue calculations near the phase attractor. The results are close t o the experimental observations.