Finite-temperature phase diagram of nonmagnetic impurities in high-temperature superconductors using a d=3 tJ model with quenched disorder

摘要

We study a quenched disordered d=3 tJ Hamiltonian with static vacancies as amodel of nonmagnetic impurities in high-Tc materials. Using a position-spacerenormalization-group approach, we calculate the evolution of thefinite-temperature phase diagram with impurity concentration p, and findseveral features with close experimental parallels: away from half-filling wesee the rapid destruction of a spin-singlet phase (analogous to thesuperconducting phase in cuprates) which is eliminated for p > 0.05; in thesame region for these dilute impurity concentrations we observe an enhancementof antiferromagnetism. The antiferromagnetic phase near half-filling is robustagainst impurity addition, and disappears only for p > 0.40.